Surgical Strategy and Prognostic Factors in Very Elderly (≥75 Years) Patients with Stage I NSCLC: Insights From a Propensity Score–Matched Analysis

Surgical Strategy and Prognostic Factors in Very Elderly (≥75 Years) Patients with Stage I NSCLC: Insights From a Propensity Score–Matched Analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Surgical Strategy and Prognostic Factors in Very Elderly (≥75 Years) Patients with Stage I NSCLC: Insights From a Propensity Score–Matched Analysis Jui-Ying Lee, Min-Fang Chao, Yi-Wen Shen, Shih-Yu Kao, Yu-Ting Lo, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8301020/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 07 Apr, 2026 Read the published version in BMC Pulmonary Medicine → Version 1 posted 12 You are reading this latest preprint version Abstract Background The optimal surgical strategy for very elderly patients (≥ 75 years) with stage I non–small cell lung cancer (NSCLC) remains uncertain. Methods We retrospectively analyzed 390 patients with pathologic stage I NSCLC (≤ 4 cm, N0) who underwent curative resection at two university-affiliated hospitals. Fifty-one patients were aged ≥ 75 years and 339 were < 75 years. Recurrence-free survival (RFS) was the primary endpoint, and overall survival (OS) was secondary. Propensity-score matching (PSM) balanced baseline factors, and multivariable Cox regression identified independent predictors of recurrence. Results Older patients had significantly worse outcomes than younger ones (5-year RFS 65% vs. 82%, p < 0.001; OS 69% vs. 92%, p < 0.001). After PSM, age ≥ 75 remained an independent predictor of recurrence (HR 2.40, p = 0.015) and overall survival (HR 4.40, p 2 cm also predicted poorer RFS (HR 3.41, p = 0.026). High-risk pathological features (poor differentiation, LVI, STAS) were predictive in the overall cohort but less so in the very elderly. Adjuvant chemotherapy had no significant effect on RFS. Conclusions In very elderly patients with stage I NSCLC, tumor size and surgical extent were the main predictors of recurrence. Lobectomy achieved superior recurrence-free survival, underscoring the importance of optimal oncologic clearance during initial surgery when adjuvant therapy is rarely feasible. surgical intervention stage I lung cancer elderly Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Lung cancer is a leading cause of cancer mortality in older adults. The incidence of early-stage NSCLC in the elderly is rising as life expectancy increases[ 1 ]. Low-dose computed tomography (LDCT) has been shown to detect lung cancer at earlier stages than conventional methods. The NLST and other trials demonstrated a 20% reduction in lung cancer mortality through LDCT screening, primarily due to increased detection of stage I disease[ 2 ]. Real-world data confirm a stage shift toward earlier diagnoses[ 3 , 4 ]. The widespread use of LDCT has increased the detection of stage I lung cancers, including a growing number in elderly patients[ 5 ]. Surgical resection remains the standard curative treatment for stage I NSCLC, typically via lobectomy with systematic lymph node dissection[ 6 , 7 ]. A landmark randomized trial by the Lung Cancer Study Group established lobectomy as the gold standard after demonstrating that limited resection (segmentectomy or wedge) led to significantly higher local recurrence rates and worse survival[ 7 ]. However, patients ≥ 75 years (“very elderly”) pose a unique clinical challenge – they often have increased operative risks and competing comorbidities, leading some surgeons to consider less extensive resections or non-surgical therapies in this age group[ 8 – 10 ]. In recent years, lung-sparing surgery has gained renewed interest for small, early-stage tumors. Two major phase III trials have shown that sublobar resection can achieve outcomes comparable to lobectomy in selected patients with tumors ≤ 2 cm. The CALGB 140503 (Alliance) trial randomized patients with peripheral clinical T1aN0 tumors ≤ 2 cm to lobectomy versus sublobar resection and found no significant difference in 5-year disease-free survival (63.6% vs 64.1%); establishing non-inferiority of sublobar resection for small tumors[ 11 ]. However, sublobar resection was associated with a roughly three-fold higher local recurrence rate in that study. Similarly, the JCOG0802/WJOG4607L trial in Japan (median patient age 71) focused on anatomic segmentectomy for peripheral tumors ≤ 2 cm and demonstrated superior overall survival with segmentectomy (5-year OS 94.3% vs. 91.1% for lobectomy, p < 0.01) while 5-year relapse-free survival was equivalent (88.0% vs 87.9%)[ 12 ]. These trials, which predominantly enrolled patients in their 60s and early 70s, suggest that for small tumors an anatomic sublobar resection (especially segmentectomy) can be an oncologically sound approach in fit patients. Despite these advances, very elderly patients (≥ 75 years) have been underrepresented in clinical trials, and optimal surgical management in this age group remains uncertain. Elderly-specific studies have shown mixed results[ 8 , 9 , 13 – 17 ]. For example, a meta-analysis of stage I NSCLC patients ≥ 70 years found no significant difference in 5-year OS between lobectomy and sublobar resection, suggesting that limited resection can yield comparable survival in older patients[ 10 ]. However, OS may be a misleading endpoint in the elderly due to high competing mortality from non-cancer causes. It remains unclear whether recurrence-free survival (RFS) – a metric focusing on cancer control – is compromised by lesser resection in very old patients. Notably, most octogenarians are unable to tolerate adjuvant therapies like chemotherapy, making the initial surgical approach crucial. Some reports indicate that wedge resection (a non-anatomic sublobar resection) has higher local recurrence rates than segmentectomy. If wedge resections are more frequently performed in frail older patients, this could negatively impact their cancer outcomes. In this study, we aimed to determine the key risk factors for RFS in very elderly patients with stage I NSCLC, with particular focus on the oncologic impact of surgical extent (lobectomy versus sublobar resection). Our goal was to inform surgical decision-making for very elderly patients with early lung cancer and to assess whether less extensive resection truly provides equivalent cancer control in this high-risk group. Methods Study Design and Patient Selection We performed a retrospective cohort study of patients who underwent curative-intent resection for pathological stage I NSCLC at two university-affiliated hospitals between 2016 and 2019. Inclusion criteria were: (a) age 18 or older; (b) pathological stage I NSCLC (per 8th Edition AJCC TNM classification, tumor ≤ 4 cm, N0, M0); (c) receipt of either lobectomy or sublobar resection (segmentectomy or wedge) as the primary surgery; and (d) no neoadjuvant therapy. Patients with incomplete resection (R1 or R2) were excluded. For the primary analyses, patients were stratified by age into two groups: <75 years (younger cohort) and ≥ 75 years (“very elderly”). All patients underwent intraoperative hilar and mediastinal lymph node evaluation (systematic dissection or sampling) per standard oncologic practice. The final study cohort consisted of 390 patients meeting the above criteria, including 51 patients aged ≥ 75 years and 339 patients aged < 75 years. The study was conducted in accordance with the Declaration of Helsinki, and approved by the Institutional Review Board of Kaohsiung Medical University Hospital (KMUH) (KMUHIRB-E(I)-20240126) Clinical Variables and Definitions Patient demographics and clinical variables were obtained from medical records. These included age at surgery, sex, smoking history, and Eastern Cooperative Oncology Group (ECOG) performance status. Comorbid conditions were qualitatively noted (formal comorbidity indices were not uniformly available). Tumor characteristics were extracted from pathology reports, including tumor size in millimeters; histologic subtype (adenocarcinoma vs. other NSCLC subtypes); tumor differentiation grade (well or moderate differentiation [Grade 1–2] vs. poor differentiation [Grade 3]); lymphovascular invasion (LVI, presence vs. absence); spread through air spaces (STAS, presence vs. absence); and visceral pleural invasion (PL0 vs. PL1/PL2). Surgical extent was categorized as lobectomy versus sublobar resection (segmentectomy or wedge). When available, we noted whether a sublobar case was an anatomic segmentectomy or a wedge resection. Use of adjuvant chemotherapy was recorded (although all patients were pathologic N0; only a few with stage IB or other high-risk features received adjuvant chemotherapy per institutional practice). Outcome Measures The primary endpoint was recurrence-free survival (RFS) , defined as the time from surgery to first recurrence (locoregional or distant) or death from any cause. Patients alive without recurrence were censored at last follow-up. Statistical Analysis Baseline characteristics were compared between groups using chi-square or Fisher’s exact tests for categorical variables and independent-samples t -tests for continuous variables. We first compared patients aged ≥ 75 versus < 75 to identify any systematic differences by age. We also compared lobectomy vs. sublobar subgroups to assess potential selection biases. Survival curves for RFS and OS were estimated by the Kaplan–Meier method. Differences between groups were assessed with the log-rank test. We constructed Kaplan–Meier curves stratified by age group and by surgical extent. In particular, we plotted RFS curves for the ≥ 75 cohort stratified by lobectomy vs. sublobar resection to visualize differences in recurrence outcomes between surgical approaches. We used Cox proportional hazards regression to identify independent prognostic factors for RFS (and, in a parallel analysis, for OS). Each candidate variable (age group, sex, smoking status, ECOG, tumor size category, differentiation grade, histology, LVI, STAS, pleural invasion, surgical extent, and adjuvant chemotherapy) was first tested in univariate Cox models. Variables with p < 0.10 in univariate analysis were considered for inclusion in multivariable models. For the overall cohort, a stepwise multivariable Cox model was constructed to determine independent predictors of RFS. Given the limited sample size in the ≥ 75 subgroup ( n = 51), we built a focused multivariable model for that subgroup including the key variables of interest (surgical extent and tumor size) and any other covariates that showed a suggestive association in univariate analysis. Hazard ratios (HR) with 95% confidence intervals (CI) were calculated for each factor. Propensity Score–Matched Analysis : To further account for confounding differences between older and younger patients, we performed a propensity score matching analysis. Patients aged ≥ 75 were matched 1:1 to patients < 75 based on baseline factors including pathologic stage (IA vs. IB), sex, ECOG performance status, and smoking history. Nearest-neighbor matching without replacement was applied (a caliper of 0.2 standard deviations was tested but ultimately not used, as it reduced balance in some covariates). This yielded 51 matched pairs (102 patients) with well-balanced covariates. Outcomes (RFS and OS) were then compared between the matched ≥ 75 and < 75 groups, effectively isolating the impact of age on outcomes under similar tumor and health conditions. We also explored the impact of surgical extent within each age stratum. Due to the smaller sample, a separate PSM within the ≥ 75 group (matching lobectomy vs. sublobar patients) was not feasible; instead, we used multivariable adjustment in that subgroup to assess the effect of lobectomy vs. sublobar resection on RFS. Similarly, we examined lobectomy vs. sublobar outcomes in patients < 75 for comparison. All statistical tests were two-sided, and p < 0.05 was considered statistically significant. Analyses were performed using SPSS v25 (IBM Corp) and R v4.0 (R Foundation for Statistical Computing). The study was approved by the institutional review boards of the participating hospitals, with a waiver of individual consent for deceased or lost patients given the retrospective design. Results Patient Characteristics A total of 390 patients met the inclusion criteria for pathologic stage I NSCLC resection (Table 1 ). Of these, 51 patients (13.1%) were ≥ 75 years (very elderly group), with a median age of 78 (range 75–87), and the remaining 339 patients (86.9%) were < 75 years (younger group), median age 63 (range 32–74). Baseline characteristics differed in a few notable ways between the age groups. Older patients were more likely to have a history of smoking (39.2% vs. 24.2% for < 75, p = 0.03) and had a higher proportion of squamous cell carcinoma or other non-adenocarcinoma histology (15.7% of ≥ 75 patients vs. 3.5% of < 75, p 3 cm) was also more frequent in the ≥ 75 group (54.9% vs. 35.1% in < 75, p = 0.010), indicating that tumors tended to be larger in the elderly cohort despite similar inclusion criteria. In contrast, use of lobectomy vs. sublobar resection did not significantly differ by age – in both groups approximately half of patients underwent lobectomy and half underwent sublobar resection (51.0% lobectomy in ≥ 75 vs. 51.3% in < 75, p = 1.00). This suggests surgeons did not uniformly favor a sublobar approach in the elderly, possibly reflecting careful case selection. Other variables such as sex distribution, ECOG performance status, and incidence of high-grade tumors or LVI were similar between age groups ( p > 0.1 for each), except for a trend toward higher STAS incidence in older patients (37.3% vs. 24.2%, p = 0.070). Adjuvant chemotherapy was administered to 11 of 51 older patients (21.6%) and 48 of 339 younger patients (14.2%); this difference was not statistically significant ( p = 0.24), indicating broadly comparable adjuvant treatment rates across ages. Table 1 Baseline characteristics of the entire cohort (390 patients) stratified by age group. Values are given as number of patients (%) in each category. Variable < 75 years (N = 339) ≥ 75 years (N = 51) p-value Gender Female 197 (58.1%) 23 (45.1%) 0.1105 Male 142 (41.9%) 28 (54.9%) – ECOG performance status 0.2411 0 64 (18.9%) 7 (13.7%) – 1 271 (79.9%) 42 (82.4%) – 2–3 4 (1.2%) 2 (3.9%) – Smoking history 0.0352* No 257 (75.8%) 31 (60.8%) – Yes 82 (24.2%) 20 (39.2%) – Clinical stage (pre-op) 0.1307 0 4 (1.2%) 0 (0%) – I 278 (82.0%) 38 (74.5%) – II 17 (5.0%) 4 (7.8%) – III 21 (6.2%) 6 (11.8%) – IV 5 (1.5%) 3 (5.9%) – Unknown 14 (4.1%) 0 (0%) – Operation type 1.0000 Lobectomy 174 (51.3%) 26 (51.0%) – Sublobar resection 165 (48.7%) † 25 (49.0%) † – Pathologic stage 0.0103* IA 220 (64.9%) 23 (45.1%) – IB 119 (35.1%) 28 (54.9%) – Tumor differentiation 0.7087 Grade 1–2 (well/mod) 247 (72.9%) 39 (76.5%) – Grade 3 (poor) 92 (27.1%) 12 (23.5%) – Histologic type 0.0009*** Adenocarcinoma 327 (96.5%) 43 (84.3%) – Non-adenocarcinoma ‡ 12 (3.5%) 8 (15.7%) – Lymphovascular invasion 0.8043 No 313 (92.3%) 46 (90.2%) – Yes 26 (7.7%) 5 (9.8%) – Spread through air spaces 0.0696 No 257 (75.8%) 32 (62.7%) – Yes 82 (24.2%) 19 (37.3%) – Tumor size (largest diameter) 0.0019** ≤ 20 mm 226 (66.7%) 22 (43.1%) – > 20 mm and ≤ 40 mm 113 (33.3%) 29 (56.9%) – Visceral pleural invasion 0.0590 PL0 (none) 235 (69.3%) 28 (54.9%) – PL1/PL2 104 (30.7%) 23 (45.1%) – Adjuvant chemotherapy 0.2431 No 291 (85.8%) 40 (78.4%) – Yes 48 (14.2%) 11 (21.6%) – p < 0.05; ** p < 0.01; *** p < 0.001. † “Sublobar” includes both wedge resection and segmentectomy. ‡ Non-adenocarcinoma histologies in this series included squamous cell carcinoma, large cell carcinoma, pleomorphic carcinoma, lymphoepithelial carcinoma, basaloid squamous carcinoma, and adenosquamous carcinoma. ECOG: Eastern Cooperative Oncology Group performance status; LVI: lymphovascular invasion; STAS: spread through air spaces; PL: visceral pleural invasion. Propensity Score–Matched Analysis by Age To ensure comparability of the two age groups, we performed a propensity score–matched (PSM) analysis. Table 2 summarizes baseline characteristics for the 51 matched pairs of older (≥ 75) and younger (< 75) patients after matching on sex, clinical stage, ECOG, and smoking history. As expected, the matching procedure eliminated most baseline differences. In the matched subset, there were no significant differences between the ≥ 75 and 0.2, except a borderline difference in differentiation grade). Standardized mean differences (SMD) for all matched covariates were below 0.1, indicating adequate balance. Notably, even in the matched groups, the proportion of lobectomy versus sublobar resection remained similar (51% vs. 58.8% lobectomy in ≥ 75 and < 75, respectively, p = 0.55), confirming that surgical extent was not heavily biased by age in our cohort. The only baseline variable with a suggestion of imbalance after matching was tumor differentiation: 76.5% of older patients had grade 1–2 tumors vs. 58.8% of younger (p = 0.090, SMD 0.377), though this did not reach significance. Overall, the PSM analysis indicates that the younger and very elderly patients in our study could be fairly compared, having similar baseline tumor stages and health status after matching. Table 2 Baseline characteristics in the propensity score–matched subset (51 pairs) of patients < 75 vs. ≥75 years. Variable < 75 years (N = 51) ≥75 years (N = 51) p-value SMD Gender 1.0000 0.0390 Female 22 (43.1%) 23 (45.1%) – – Male 29 (56.9%) 28 (54.9%) – – ECOG status 0.8415 0.1160 0 7 (13.7%) 7 (13.7%) – – 1 43 (84.3%) 42 (82.4%) – – 2–3 1 (2.0%) 2 (3.9%) – – Smoking history 1.0000 0.0400 No 30 (58.8%) 31 (60.8%) – – Yes 21 (41.2%) 20 (39.2%) – – Clinical stage (pre-op) 0.9843 0.0780 I 37 (72.5%) 38 (74.5%) – – II 4 (7.8%) 4 (7.8%) – – III 6 (11.8%) 6 (11.8%) – – IV 4 (7.8%) 3 (5.9%) – – Operation type 0.5505 0.1580 Lobectomy 30 (58.8%) 26 (51.0%) – – Sublobar resection † 21 (41.2%) 25 (49.0%) – – Pathologic stage 0.4283 0.1960 IA 28 (54.9%) 23 (45.1%) – – IB 23 (45.1%) 28 (54.9%) – – Tumor differentiation 0.0904 0.3770 Grade 1–2 (well/mod) 30 (58.8%) 39 (76.5%) – – Grade 3 (poor) 21 (41.2%) 12 (23.5%) – – Histologic type 0.2017 0.3160 Adenocarcinoma 48 (94.1%) 43 (84.3%) – – Non-adenocarcinoma‡ 3 (5.9%) 8 (15.7%) – – Lymphovascular invasion 1.0000 0.0630 No 45 (88.2%) 46 (90.2%) – – Yes 6 (11.8%) 5 (9.8%) – – Spread through air spaces 0.6766 0.1240 No 35 (68.6%) 32 (62.7%) – – Yes 16 (31.4%) 19 (37.3%) – – Tumor size 1.0000 0.0000 ≤20 mm 22 (43.1%) 22 (43.1%) – – >20 mm and ≤ 40 mm 29 (56.9%) 29 (56.9%) – – Visceral pleural invasion 1.0000 0.0390 PL0 (none) 29 (56.9%) 28 (54.9%) – – PL1/PL2 22 (43.1%) 23 (45.1%) – – Adjuvant chemotherapy 0.4359 0.2060 No 44 (86.3%) 40 (78.4%) – – Yes 7 (13.7%) 11 (21.6%) – – † “Sublobar” includes wedge resection and segmentectomy. ‡ Non-adenocarcinoma histologies include those listed in Table 2 . No significant differences were observed after matching. SMD: standardized mean difference. The PSM results confirm that after matching, the older and younger cohorts were well balanced in terms of key baseline factors. This allowed for a fair comparison of outcomes by age, as described below. Survival Outcomes by Age Group With a median follow-up of 63.7 months for surviving patients, oncologic outcomes were significantly worse in the very elderly group. Figure 1 shows the Kaplan–Meier RFS curves stratified by age. RFS ( Fig. 1 A ) and OS ( Fig. 1 B ) in patients < 75 vs ≥ 75 years old with stage I NSCLC. Patients ≥ 75 experienced a sharp drop in RFS in the first 2–3 years after surgery. The 5-year RFS was only 64.7% in the ≥ 75 group vs. 81.9% in the < 75 group (log-rank p 0.0011). Overall survival was even more dramatically lower in the ≥ 75 cohort: 5-year OS was 69.1% for ≥ 75 vs. 91.5% for < 75 (log-rank p < 0.0001). These differences remained significant even after accounting for baseline factors. RFS in patients < 75 vs ≥ 75 years old with stage I NSCLC (PSM). In the propensity-matched subset, age ≥ 75 was still associated with significantly worse RFS ( p = 0.042) ( Fig. 2 A ) and markedly worse OS ( p = 0.0024) ( Fig. 2 B ). compared to < 75. In the matched analysis, 5-year RFS was approximately 64.7% in ≥ 75 vs. 81.6% in < 75, and 5-year OS 69.1% vs. 91.8%, respectively. Thus, very advanced age itself emerged as a strong adverse prognostic factor for both recurrence and survival, even when controlling for tumor stage and health status. Risk Factors for Recurrence – Cox Regression Analysis (Overall Cohort after PSM) To identify factors contributing to recurrence risk, we performed Cox proportional hazards analyses for RFS. In the multivariate Cox model ( Table 3 ) , age ≥ 75 years remained a significant independent predictor of worse RFS (HR 2.40, 95% CI 1.19–4.84, p = 0.0146). In practical terms, even after adjusting for tumor factors, patients in the ≥ 75 group had more than double the hazard of recurrence or death compared to those < 75. Lymphovascular invasion (LVI) was another strong prognostic factor: patients with LVI-positive tumors had an almost five-fold higher hazard of recurrence (HR 4.64, 95% CI 1.69–12.75, p = 0.0030) compared to those without LVI. Tumor size was also critical – tumors > 20 mm (within stage I, roughly corresponding to stage IB vs. IA) carried a significantly higher recurrence risk (HR 3.38, 95% CI 1.37–8.31, p = 0.0081) than tumors ≤ 20 mm. In contrast, surgical extent (lobectomy vs. sublobar) was not an independent predictor of RFS in the overall analysis (HR 1.61 for sublobar vs. lobectomy, 95% CI 0.83–3.13, p = 0.1570). This suggests that when all ages are considered together and other factors are controlled, choosing a sublobar resection did not significantly increase recurrence risk in the general stage I population. Other variables, such as tumor differentiation grade, histology, STAS, pleural invasion, and adjuvant chemotherapy, were not significant predictors of RFS in this multivariable model. Notably, adjuvant chemotherapy showed no clear benefit (HR 0.36, p = 0.14 in multivariate analysis), consistent with its infrequent use and likely selection for higher-risk cases. Table 3 Cox proportional hazards analysis of recurrence-free survival (RFS) in stage I NSCLC (overall cohort) after propensity score matching. Both univariate and multivariate results are shown. Hazard ratios > 1 indicate higher hazard of recurrence (worse RFS). Variable Univariate HR (95% CI) Univariate p value Multivariate HR (95% CI) Multivariate P value Age group (≥ 75 vs. <75) 2.17 (1.04–4.52) 0.0387* 2.40 (1.19–4.84) 0.0146* Operation type (sublobar vs. lobar) 1.33 (0.69–2.56) 0.3980 1.61 (0.83–3.13) 0.1570 Differentiation (Grade 3 vs. 1–2) 1.75 (0.87–3.54) 0.1180 – – Histology (non-adenoca. vs. adeno) 1.67 (0.63–4.43) 0.3040 1.30 (0.39–4.30) 0.6650 Lymphovascular invasion (Yes vs. No) 2.88 (1.31–6.31) 0.0084** 4.64 (1.69–12.75) 0.0030** Spread through air spaces (Yes vs. No) 1.60 (0.79–3.23) 0.1930 – – Tumor size (> 20 mm vs. ≤20 mm) 2.17 (0.89–5.27) 0.0865 3.38 (1.37–8.31) 0.0081** Visceral pleural inv. (PL1/2 vs. PL0) 1.06 (0.57–1.94) 0.8620 – – Adjuvant chemotherapy (Yes vs. No) 0.99 (0.38–2.60) 0.9840 0.36 (0.09–1.39) 0.1370 p < 0.05; ** p < 0.01. (Variables with “–” in the multivariate columns were not included in the final multivariate model, as their univariate p ≥ 0.10 or they were removed during model selection.) HR: hazard ratio; CI: confidence interval. In summary, for the overall stage I cohort, advanced age (≥ 75), presence of LVI, and larger tumor size were the dominant risk factors for recurrence, whereas the choice of lobectomy vs. sublobar resection was not a significant determinant of RFS when younger and older patients were analyzed together. This overall analysis, however, masks an important age interaction effect, as explored next. Subgroup Analysis: Very Elderly (≥ 75 Years) Patients Given the stark differences in outcomes by age and our hypothesis that surgical extent might especially impact the very elderly, we conducted a subgroup analysis focusing on the 51 patients aged ≥ 75 years. We evaluated prognostic factors for RFS within this ≥ 75 group ( Table 4 ) and examined the effect of lobectomy vs. sublobar resection on outcomes in these patients. In univariate analysis among patients ≥ 75, some covariates showed notable effects on RFS, although the small sample limited statistical power. Most importantly, surgical extent demonstrated a strong trend: sublobar resection had a 2.56-fold higher hazard of recurrence compared to lobectomy (HR 2.56, 95% CI 0.97–6.76, p = 0.057) in univariate analysis, narrowly missing conventional significance. After adjusting for tumor size and other factors in a multivariable Cox model, limited resection emerged as a significant independent predictor of worse RFS (adjusted HR 3.57, 95% CI 1.02–12.51, p = 0.0462). In other words, an elderly patient who underwent a sublobar resection had over 3.57 times higher risk of recurrence than a similar patient who had a lobectomy, when controlling for tumor size and pathology. This is a critical finding, indicating that in very elderly patients the extent of surgical resection significantly impacts oncologic outcomes, with lobectomy conferring superior long-term RFS. Other factors in the ≥ 75 subgroup analysis included tumor size, which was identified as an important prognostic factor despite a modest univariate effect. Patients with tumors > 20 mm appeared to have worse RFS than those with ≤ 20 mm tumors (univariate HR 1.64, p = 0.316, not significant). However, in the multivariate model that accounted for surgical extent and other variables, tumor size > 2 cm became a significant independent predictor of shorter RFS (adjusted HR 3.41, 95% CI 1.16–10.0, p = 0.0256). Thus, in very elderly patients, having a tumor larger than 2 cm was associated with a more than three-fold higher hazard of recurrence, after adjusting for surgery type and other factors. By contrast, many pathological features that were prognostic in the overall cohort did not significantly stratify the ≥ 75 patients. For example, LVI, STAS, and poor differentiation did not show an association with higher recurrence in the elderly group (indeed, the hazard ratios for LVI and STAS were < 1 in this subgroup, albeit with wide confidence intervals and non-significant p -values). This suggests that the adverse impact of these features was attenuated in very elderly patients, possibly due to the overriding influence of other factors or simply limited sample size. Patient sex, smoking history, and ECOG performance status were also not significantly associated with RFS in ≥ 75 patients. Table 4 Cox proportional hazards analysis of recurrence-free survival (RFS) in very elderly patients (≥ 75 years, n = 51). The multivariate model for this subgroup included surgical extent and tumor size, as well as other covariates of interest. Variable Univariate HR (95% CI) Univariate P value Multivariate HR (95% CI) Multivariate P value Gender (Male vs. Female) 1.64 (0.65–4.18) 0.2970 – – Smoking history (Yes vs. No) 1.20 (0.48–2.99) 0.6960 – – ECOG (1 vs. 0) 0.56 (0.18–1.71) 0.3090 – – ECOG (2–3 vs. 0) 1.26 (0.14–11.46) 0.8360 – – Operation type (sublobar vs. lobar) 2.56 (0.97–6.76) 0.0568 3.57 (1.02–12.51) 0.0462* Histology (non-adenoca. vs. adeno) 1.11 (0.32–3.82) 0.8660 2.26 (0.50–10.19) 0.2880 Differentiation (Grade 3 vs. 1–2) 0.77 (0.25–2.31) 0.6360 – – Lymphovascular invasion (Yes vs. No) 0.56 (0.07–4.21) 0.5720 – – Spread through air spaces (Yes vs. No) 0.80 (0.31–2.03) 0.6390 – – Tumor size (> 20 mm vs. ≤20 mm) 1.64 (0.62–4.34) 0.3160 3.41 (1.16–10.0) 0.0256* Visceral pleural inv. (PL1/2 vs. PL0) 0.46 (0.18–1.22) 0.1210 0.45 (0.16–1.28) 0.1360 Adjuvant chemotherapy (Yes vs. No) 0.61 (0.18–2.11) 0.4370 0.67 (0.17–2.67) 0.5730 p < 0.05. HR: hazard ratio; CI: confidence interval. (Univariate HRs are not shown for reference categories such as ECOG 0, lobectomy, etc. Multivariate model included surgical extent, tumor size, histology, pleural invasion, and chemotherapy; other variables were not included due to non-significance or model parsimony.) This analysis highlights that in our very elderly cohort, the extent of resection and tumor size were the primary drivers of recurrence risk, whereas other tumor features played a lesser role. Surgical Extent and Recurrence-Free Survival in very elderly patients To illustrate the impact of surgical extent on outcomes in both age groups, we plotted Kaplan–Meier RFS curves for lobectomy versus sublobar resection ( Fig. 3 ) Among the 51 very elderly patients (≥ 75 years), 26 underwent lobectomy and 25 underwent sublobar resection. The RFS curves separated distinctly between these subgroups. At 5 years post-surgery, RFS was 76.6% for patients who underwent lobectomy compared with 50.8% for those who had sublobar resection ( p = 0.048). Most recurrences in the elderly sublobar group occurred within the first 2–3 years, whereas the lobectomy group’s RFS curve plateaued at a higher level, indicating superior long-term cancer control with lobectomy. The finding reinforce that, in very elderly patients, a full lobar resection provides a measurable oncologic benefit in preventing recurrence compared with limited resection. Tumor Size and Recurrence-Free Survival in the Elderly Beyond surgical extent, tumor size emerged as a critical prognostic factor in the very elderly in Fig. 4 . Within stage I disease, a cutoff of 2 cm, delineated distinct risk strata. In the ≥ 75-year cohort, tumors larger than 2 cm were independently associated with shorter RFS in multivariable Cox analysis (HR 3.41, 95% CI 1.16–10.0, p = 0.026; Table 4 ). Although the difference in absolute 5-year RFS did not reach statistical significance (55% vs 80.6%, p = 0.31; Fig. 5 ), a clear trend toward poorer outcomes with increasing tumor size was observed. The adverse effect of larger tumor size was particularly evident when combined with limited resection. Among elderly patients with tumors > 2 cm, sublobar resection was associated with the highest recurrence risk, whereas lobectomy may mitigate much of this size-related disadvantage. Conversely, for tumors ≤ 2 cm, sublobar resection yielded relatively acceptable disease control—albeit in a smaller subset—consistent with the notion that small, peripheral tumors may be adequately managed with anatomical segmentectomy when lobectomy is not feasible. These findings reinforce the importance of integrating tumor size and physiological fitness into individualized surgical planning for very elderly patients with stage I NSCLC. Postoperative Chemotherapy in the Elderly Among the very elderly cohort, only 11 patients received adjuvant chemotherapy, while 40 did not. At 5 years after surgery, RFS was 72.7% in patients who received chemotherapy compared with 62.3% in those who did not ( p = 0.43) in Fig. 5 . Other Prognostic Factors in the Elderly Other pathological factors did not significantly stratify recurrence risk in the ≥ 75 group. Poor differentiation, LVI, STAS, and visceral pleural invasion, which were adverse features in the overall cohort, showed attenuated or no effect in the elderly cohort. Discussion This study examined outcomes in very elderly patients (≥ 75 years) with pathologic stage I NSCLC and demonstrated that surgical extent strongly influenced recurrence-free survival (RFS). In this population, lobectomy was associated with significantly superior recurrence control compared with sublobar resection, whereas this effect was not observed in patients younger than 75 years. These findings underscore that, although sublobar resection has been validated as oncologically adequate in selected younger patients with small tumors, its effectiveness may be diminished in very elderly patients. Our results extend prior randomized evidence from CALGB 140503 and JCOG0802, which demonstrated the non-inferiority of sublobar resection for tumors ≤ 2 cm in predominantly younger cohorts[ 11 , 12 , 18 ]. Importantly, these landmark trials included few patients ≥ 75 years, limiting their applicability to this population. The present study suggests that age may modify the oncologic adequacy of sublobar resection. One plausible explanation is that wedge resections are more frequently performed in elderly patients due to frailty or impaired pulmonary reserve. Wedge resections, lacking anatomical precision and comprehensive nodal evaluation, are consistently associated with higher local recurrence rates compared with segmentectomy[ 19 ]. This likely contributed to the inferior outcomes observed in elderly patients who underwent sublobar resection. Several pathological features were prognostic for shorter RFS in the overall stage I lung cancer cohort but did not significantly stratify recurrence risk in patients aged ≥ 75 years. Poor differentiation, lymphovascular invasion (LVI), spread through air spaces (STAS), and visceral pleural invasion—all adverse factors in the younger population[ 20 – 22 ]—showed attenuated or no effect in the very elderly. This attenuation may reflect limited statistical power due to the smaller sample size, or it may represent a true biological difference, such as inherently less aggressive tumor behavior in the very elderly or the predominance of competing non-cancer risks that overshadow the prognostic impact of tumor-related factors. Another critical factor is the limited role of adjuvant chemotherapy in the very elderly. Published studies have suggested that adjuvant chemotherapy can improve prognosis after standard lung cancer surgery, even in patients over 75 years with early-stage NSCLC[ 23 , 24 ]. However, in our cohort, only a minority of patients ≥ 75 years received systemic therapy. As a result, microscopic residual disease following limited resection was seldom addressed, in contrast to younger patients where adjuvant treatment may partially mitigate oncologic risk. This underscores the importance of achieving complete oncologic clearance through surgery in elderly patients, for whom systemic therapy is often not feasible. Notably, advanced age itself remained an independent predictor of recurrence, even after adjusting for tumor size and pathologic risk factors. This observation suggests that host-related factors such as immunosenescence, frailty, or diminished physiologic reserve may impair the ability to suppress micrometastatic disease. Thus, in very elderly patients, optimal surgical clearance may be particularly critical[ 8 , 14 , 15 , 19 ]. Our subgroup analysis further showed that tumor size > 2 cm independently predicted recurrence, especially when combined with limited resection. These findings reinforce that lobectomy should remain the preferred strategy for physiologically fit elderly patients, particularly for larger tumors. Indeed, elderly patients who underwent lobectomy in our study achieved RFS comparable to that of younger lobectomy patients, and this was accomplished without evidence of increased perioperative mortality. For patients unable to tolerate lobectomy, anatomic segmentectomy may represent a reasonable alternative, as it provides superior margins and nodal assessment compared with wedge resection[ 19 ]. However, wedge resections should be reserved for patients with prohibitive operative risks. For those deemed unfit for any surgery, stereotactic body radiotherapy (SBRT) remains an important alternative method[ 25 , 26 ]. Our findings are consistent with prior elderly-specific investigations. For instance, Chen et al. demonstrated that lobectomy conferred a survival advantage over sublobar resection in patients ≥ 75 years with stage I adenocarcinoma ≤ 3 cm[ 9 ], supporting the conclusion that more extensive resection improves cancer control in the elderly. Conversely, SEER database analyses and meta-analyses have suggested no survival difference between lobectomy and sublobar resection in elderly patients, but these studies primarily assessed overall survival (OS), which may be confounded by competing non-cancer mortality[ 16 ]. By focusing on RFS, our study provides clearer evidence that cancer control is indeed compromised by sublobar resection in very elderly patients, even if OS appears similar due to competing risks. Several limitations warrant consideration. First, this was a retrospective, two-institutional analysis with a relatively small number of patients ≥ 75 years (13% of the cohort), which may limit generalizability and statistical power. Second, the “sublobar” group combined segmentectomy and wedge resection, which are not oncologically equivalent. Although small sample size precluded separate analyses, it is likely that the higher recurrence risk was driven primarily by wedge resections. Third, detailed information on pulmonary function and frailty indices was not consistently available; thus, unmeasured confounding related to operative selection cannot be excluded. Nevertheless, the fact that recurrence—not only OS—was significantly higher in elderly patients undergoing sublobar resection suggests a true oncologic disadvantage rather than survival bias alone. In conclusion, our study demonstrates that lobectomy provides superior recurrence control compared with sublobar resection in very elderly patients with stage I NSCLC, particularly for tumors > 2 cm, without evidence of increased perioperative risk. These findings support lobectomy as the preferred surgical approach for fit elderly patients whenever feasible. For patients unable to tolerate lobectomy, anatomic segmentectomy is preferable to wedge resection. Future prospective studies focusing specifically on patients ≥ 75 years are needed to confirm these results and to refine surgical guidelines for this growing patient population. Declarations CRediT authorship contribution statement Conceptualization: Chih-Jen Yang, Jen-Yu Hung, Inn-Wen Chong, Jui-Ying Lee; Data collection : Yu-Ting Lo, Yu-Wei Liu, Tai-Huang Lee, Hui-Yang Hung, Cheng-Hao Chuang, Wei-An Lai ; Data analysis and interpretation of results : Yi-Wen Shen, Shih-Yu Kao. Draft manuscript preparation: Jui-Ying Lee, Min-Fang Chao, Inn-Wen Chong, Chih-Jen Yang; All authors reviewed the results and approved the final version of the manuscript. Funding: none Data availability: The datasets used and/or analyzed are available from the corresponding author on reasonable request. Consent for publication: Not applicable. Declaration of Competing Interest The authors declare that they have no conflicts of interest. Ethics approval and consent to participate: The study was conducted in accordance with the Declaration of Helsinki, and approved by the Institutional Review Board of Kaohsiung Medical University Hospital (KMUH) (KMUHIRB-E(I)-20240126) Clinical trial number: not applicable. Acknowledgments We thank staff members of the Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan. References Thai AA, Solomon BJ, Sequist LV, Gainor JF, Heist RS. Lung cancer. Lancet. 2021;398(10299):535–54. 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Lancet Respir Med. 2024;12(2):141–52. Lu G, Xiang Z, Zhou Y, Dai S, Tong F, Jiang R, Dai M, Zhang Q, Zhang D. Comparison of lobectomy and sublobar resection for stage I non-small cell lung cancer: a meta-analysis based on randomized controlled trials. Front Oncol. 2023;13:1261263. Rudasill S, Farjah F. Surgical Therapy for Stage I Lung Cancer-Lobar Versus Sublobar Resection. Semin Respir Crit Care Med 2025. Bravo-Iniguez C, Perez Martinez M, Armstrong KW, Jaklitsch MT. Surgical resection of lung cancer in the elderly. Thorac Surg Clin. 2014;24(4):371–81. Chen C, Ni Q, Shi Y, Fu S, Pan X, Wang Y, Yang J, Wang R. Prognosis analysis of lobectomy and sublobar resection in patients >/=75 years old with pathological stage I invasive lung adenocarcinoma of =3 cm: a propensity score matching-based analysis</at. Transl Cancer Res. 2019;8(2):574–82. Dong S, Roberts SA, Chen S, Zhong X, Yang S, Qu X, Xu S. 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Survival following segmentectomy or lobectomy in elderly patients with early-stage lung cancer. Oncotarget. 2016;7(14):19081–6. Zhang Z, Feng H, Xiao F, Liu D. Limited resection in clinical stage I non-small cell lung cancer patients aged 75 years old or more: a meta-analysis. Ann Transl Med. 2018;6(18):359. Li Y, Hu S, Xie J, Zhang X, Zong Y, Xu B, Li C. Effects of surgery on survival of elderly patients with stage I small-cell lung cancer: analysis of the SEER database. J Cancer Res Clin Oncol. 2019;145(9):2397–404. Ng J, Masuda Y, Ng JJ, Leow L, Choong A, Mithiran H. Lobar versus Sublobar Resection in the Elderly for Early Lung Cancer: A Meta-Analysis. Thorac Cardiovasc Surg. 2022;70(3):217–32. Hattori A, Suzuki K, Takamochi K, Wakabayashi M, Sekino Y, Tsutani Y, Nakajima R, Aokage K, Saji H, Tsuboi M, et al. Segmentectomy versus lobectomy in small-sized peripheral non-small-cell lung cancer with radiologically pure-solid appearance in Japan (JCOG0802/WJOG4607L): a post-hoc supplemental analysis of a multicentre, open-label, phase 3 trial. Lancet Respir Med. 2024;12(2):105–16. Wang P, Wang S, Liu Z, Sui X, Wang X, Li X, Qiu M, Yang F. Segmentectomy and Wedge Resection for Elderly Patients with Stage I Non-Small Cell Lung Cancer: A Systematic Review and Meta-Analysis. J Clin Med 2022, 11(2). Nakagawa K, Watanabe SI, Wakabayashi M, Yotsukura M, Mimae T, Hattori A, Miyoshi T, Isaka M, Endo M, Yoshioka H, et al. Risk Factors for Locoregional Relapse After Segmentectomy: Supplementary Analysis of the JCOG0802/WJOG4607L Trial. J Thorac Oncol. 2025;20(2):157–66. Fick CN, Dunne EG, Vanstraelen S, Toumbacaris N, Tan KS, Rocco G, Molena D, Huang J, Park BJ, Rekhtman N, et al. High-risk features associated with recurrence in stage I lung adenocarcinoma. J Thorac Cardiovasc Surg. 2025;169(2):436–44. e436. Chuang CH, Liu YW, Lai WA, Shen YW, Kao SY, Wei YC, Chien CC, Hung HY, Lee JY, Chao MF et al. Impact of Spread Through Air Spaces (STAS) on Recurrence and Surgical Trends in Stage I Non-Small Cell Lung Cancer: A Real-World Cohort Study. Kaohsiung J Med Sci 2025:e70061. Yamanashi K, Okumura N, Yamamoto Y, Takahashi A, Nakashima T, Matsuoka T, Kameyama K. Adjuvant chemotherapy for elderly patients with non-small-cell lung cancer. Asian Cardiovasc Thorac Ann. 2017;25(5):371–7. Santos FN, de Castria TB, Cruz MR, Riera R. Chemotherapy for advanced non-small cell lung cancer in the elderly population. Cochrane Database Syst Rev. 2015;2015(10):CD010463. Shinde A, Li R, Kim J, Salgia R, Hurria A, Amini A. Stereotactic body radiation therapy (SBRT) for early-stage lung cancer in the elderly. Semin Oncol. 2018;45(4):210–9. Kreinbrink P, Blumenfeld P, Tolekidis G, Sen N, Sher D, Marwaha G. Lung stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer in the very elderly (>/=80years old): Extremely safe and effective. J Geriatr Oncol. 2017;8(5):351–5. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 07 Apr, 2026 Read the published version in BMC Pulmonary Medicine → Version 1 posted Editorial decision: Revision requested 11 Feb, 2026 Reviews received at journal 09 Feb, 2026 Reviews received at journal 30 Jan, 2026 Reviews received at journal 22 Jan, 2026 Reviewers agreed at journal 22 Jan, 2026 Reviewers agreed at journal 20 Jan, 2026 Reviewers agreed at journal 19 Jan, 2026 Reviewers invited by journal 15 Jan, 2026 Editor invited by journal 01 Jan, 2026 Editor assigned by journal 10 Dec, 2025 Submission checks completed at journal 10 Dec, 2025 First submitted to journal 10 Dec, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8301020","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":576823822,"identity":"652adb3e-fa62-42cd-a67a-df7da74882e4","order_by":0,"name":"Jui-Ying Lee","email":"","orcid":"","institution":"Kaohsiung Medical University Hospital, Kaohsiung Medical University","correspondingAuthor":false,"prefix":"","firstName":"Jui-Ying","middleName":"","lastName":"Lee","suffix":""},{"id":576823824,"identity":"719d1e24-3934-4370-97f9-a04c5a266176","order_by":1,"name":"Min-Fang Chao","email":"","orcid":"","institution":"Kaohsiung Medical 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13:49:48","extension":"html","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":165466,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8301020/v1/4c0dc6851f3132e8b3f616c9.html"},{"id":100690097,"identity":"075a28a1-c7ef-4251-9d65-a26fe6d9627a","added_by":"auto","created_at":"2026-01-20 13:49:50","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":195363,"visible":true,"origin":"","legend":"\u003cp\u003eKaplan–Meier curves for recurrence-free survival (RFS; \u003cstrong\u003eFigure 1A\u003c/strong\u003e) and overall survival (OS; \u003cstrong\u003eFigure 1B\u003c/strong\u003e) in patients aged \u0026lt;75 versus ≥75 years with stage I NSCLC.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8301020/v1/b220dff827adc98c968d76f1.png"},{"id":100690180,"identity":"58709284-e050-4db8-8f9c-1338f94e29bd","added_by":"auto","created_at":"2026-01-20 13:51:20","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":190716,"visible":true,"origin":"","legend":"\u003cp\u003eKaplan–Meier curves for recurrence-free survival (RFS) in patients aged \u0026lt;75 versus ≥75 years with stage I NSCLC after propensity score matching.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8301020/v1/0cd7fa87e3d44f3a8c3aa358.png"},{"id":100690030,"identity":"48141d10-318c-4ab6-aea9-ff70d91ceaf8","added_by":"auto","created_at":"2026-01-20 13:49:36","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":90142,"visible":true,"origin":"","legend":"\u003cp\u003eRecurrence-free survival according to surgical extent (lobectomy vs sublobar resection) stratified in very elderly patients (≥75 years).\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8301020/v1/f531440a3a0b297a879ccbd3.png"},{"id":100690322,"identity":"193cd362-ab49-4a55-9a20-5e115e118304","added_by":"auto","created_at":"2026-01-20 13:52:46","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":163015,"visible":true,"origin":"","legend":"\u003cp\u003eImpact of tumor size (≤2 cm vs \u0026gt;2 cm) on recurrence-free survival in very elderly patients (≥75 years).\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8301020/v1/54ec91cea91224f3bf9650c8.png"},{"id":100690574,"identity":"ceb09416-79c5-4cef-995c-b05ba1e4f162","added_by":"auto","created_at":"2026-01-20 13:54:48","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":84547,"visible":true,"origin":"","legend":"\u003cp\u003eRecurrence-free survival according to postoperative chemotherapy use in very elderly patients (≥75 years).\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8301020/v1/241c2bf742b3324154faa6d6.png"},{"id":106809177,"identity":"cb102c89-a429-49aa-ac12-17cff659b233","added_by":"auto","created_at":"2026-04-13 16:07:39","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2479562,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8301020/v1/01662440-372d-47e3-abcc-07c25e98d4ae.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Surgical Strategy and Prognostic Factors in Very Elderly (≥75 Years) Patients with Stage I NSCLC: Insights From a Propensity Score–Matched Analysis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLung cancer is a leading cause of cancer mortality in older adults. The incidence of early-stage NSCLC in the elderly is rising as life expectancy increases[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Low-dose computed tomography (LDCT) has been shown to detect lung cancer at earlier stages than conventional methods. The NLST and other trials demonstrated a 20% reduction in lung cancer mortality through LDCT screening, primarily due to increased detection of stage I disease[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Real-world data confirm a stage shift toward earlier diagnoses[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The widespread use of LDCT has increased the detection of stage I lung cancers, including a growing number in elderly patients[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSurgical resection remains the standard curative treatment for stage I NSCLC, typically via lobectomy with systematic lymph node dissection[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. A landmark randomized trial by the Lung Cancer Study Group established lobectomy as the gold standard after demonstrating that limited resection (segmentectomy or wedge) led to significantly higher local recurrence rates and worse survival[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. However, patients\u0026thinsp;\u0026ge;\u0026thinsp;75 years (\u0026ldquo;very elderly\u0026rdquo;) pose a unique clinical challenge \u0026ndash; they often have increased operative risks and competing comorbidities, leading some surgeons to consider less extensive resections or non-surgical therapies in this age group[\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn recent years, lung-sparing surgery has gained renewed interest for small, early-stage tumors. Two major phase III trials have shown that sublobar resection can achieve outcomes comparable to lobectomy in selected patients with tumors\u0026thinsp;\u0026le;\u0026thinsp;2 cm. The CALGB 140503 (Alliance) trial randomized patients with peripheral clinical T1aN0 tumors\u0026thinsp;\u0026le;\u0026thinsp;2 cm to lobectomy versus sublobar resection and found no significant difference in 5-year disease-free survival (63.6% vs 64.1%); establishing non-inferiority of sublobar resection for small tumors[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. However, sublobar resection was associated with a roughly three-fold higher local recurrence rate in that study. Similarly, the JCOG0802/WJOG4607L trial in Japan (median patient age 71) focused on anatomic segmentectomy for peripheral tumors\u0026thinsp;\u0026le;\u0026thinsp;2 cm and demonstrated superior overall survival with segmentectomy (5-year OS 94.3% vs. 91.1% for lobectomy, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01) while 5-year relapse-free survival was equivalent (88.0% vs 87.9%)[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. These trials, which predominantly enrolled patients in their 60s and early 70s, suggest that for small tumors an anatomic sublobar resection (especially segmentectomy) can be an oncologically sound approach in fit patients.\u003c/p\u003e \u003cp\u003eDespite these advances, very elderly patients (\u0026ge;\u0026thinsp;75 years) have been underrepresented in clinical trials, and optimal surgical management in this age group remains uncertain. Elderly-specific studies have shown mixed results[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan additionalcitationids=\"CR14 CR15 CR16\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. For example, a meta-analysis of stage I NSCLC patients\u0026thinsp;\u0026ge;\u0026thinsp;70 years found no significant difference in 5-year OS between lobectomy and sublobar resection, suggesting that limited resection can yield comparable survival in older patients[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. However, OS may be a misleading endpoint in the elderly due to high competing mortality from non-cancer causes. It remains unclear whether recurrence-free survival (RFS) \u0026ndash; a metric focusing on cancer control \u0026ndash; is compromised by lesser resection in very old patients. Notably, most octogenarians are unable to tolerate adjuvant therapies like chemotherapy, making the initial surgical approach crucial. Some reports indicate that wedge resection (a non-anatomic sublobar resection) has higher local recurrence rates than segmentectomy. If wedge resections are more frequently performed in frail older patients, this could negatively impact their cancer outcomes.\u003c/p\u003e \u003cp\u003eIn this study, we aimed to determine the key risk factors for RFS in very elderly patients with stage I NSCLC, with particular focus on the oncologic impact of surgical extent (lobectomy versus sublobar resection). Our goal was to inform surgical decision-making for very elderly patients with early lung cancer and to assess whether less extensive resection truly provides equivalent cancer control in this high-risk group.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy Design and Patient Selection\u003c/h2\u003e \u003cp\u003eWe performed a retrospective cohort study of patients who underwent curative-intent resection for pathological stage I NSCLC at two university-affiliated hospitals between 2016 and 2019. Inclusion criteria were: (a) age 18 or older; (b) pathological stage I NSCLC (per 8th Edition AJCC TNM classification, tumor\u0026thinsp;\u0026le;\u0026thinsp;4 cm, N0, M0); (c) receipt of either lobectomy or sublobar resection (segmentectomy or wedge) as the primary surgery; and (d) no neoadjuvant therapy. Patients with incomplete resection (R1 or R2) were excluded. For the primary analyses, patients were stratified by age into two groups: \u0026lt;75 years (younger cohort) and \u0026ge;\u0026thinsp;75 years (\u0026ldquo;very elderly\u0026rdquo;). All patients underwent intraoperative hilar and mediastinal lymph node evaluation (systematic dissection or sampling) per standard oncologic practice.\u003c/p\u003e \u003cp\u003eThe final study cohort consisted of 390 patients meeting the above criteria, including 51 patients aged\u0026thinsp;\u0026ge;\u0026thinsp;75 years and 339 patients aged\u0026thinsp;\u0026lt;\u0026thinsp;75 years.\u003c/p\u003e \u003cp\u003e The study was conducted in accordance with the Declaration of Helsinki, and approved by the Institutional Review Board of Kaohsiung Medical University Hospital (KMUH) (KMUHIRB-E(I)-20240126)\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eClinical Variables and Definitions\u003c/h3\u003e\n\u003cp\u003e Patient demographics and clinical variables were obtained from medical records. These included age at surgery, sex, smoking history, and Eastern Cooperative Oncology Group (ECOG) performance status. Comorbid conditions were qualitatively noted (formal comorbidity indices were not uniformly available). Tumor characteristics were extracted from pathology reports, including tumor size in millimeters; histologic subtype (adenocarcinoma vs. other NSCLC subtypes); tumor differentiation grade (well or moderate differentiation [Grade 1\u0026ndash;2] vs. poor differentiation [Grade 3]); lymphovascular invasion (LVI, presence vs. absence); spread through air spaces (STAS, presence vs. absence); and visceral pleural invasion (PL0 vs. PL1/PL2). Surgical extent was categorized as lobectomy versus sublobar resection (segmentectomy or wedge). When available, we noted whether a sublobar case was an anatomic segmentectomy or a wedge resection. Use of adjuvant chemotherapy was recorded (although all patients were pathologic N0; only a few with stage IB or other high-risk features received adjuvant chemotherapy per institutional practice).\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eOutcome Measures\u003c/strong\u003e \u003cp\u003eThe primary endpoint was \u003cb\u003erecurrence-free survival (RFS)\u003c/b\u003e, defined as the time from surgery to first recurrence (locoregional or distant) or death from any cause. Patients alive without recurrence were censored at last follow-up.\u003c/p\u003e \u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003eBaseline characteristics were compared between groups using chi-square or Fisher\u0026rsquo;s exact tests for categorical variables and independent-samples \u003cem\u003et\u003c/em\u003e-tests for continuous variables. We first compared patients aged\u0026thinsp;\u0026ge;\u0026thinsp;75 versus \u0026lt;\u0026thinsp;75 to identify any systematic differences by age. We also compared lobectomy vs. sublobar subgroups to assess potential selection biases.\u003c/p\u003e \u003cp\u003eSurvival curves for RFS and OS were estimated by the Kaplan\u0026ndash;Meier method. Differences between groups were assessed with the log-rank test. We constructed Kaplan\u0026ndash;Meier curves stratified by age group and by surgical extent. In particular, we plotted RFS curves for the \u0026ge;\u0026thinsp;75 cohort stratified by lobectomy vs. sublobar resection to visualize differences in recurrence outcomes between surgical approaches.\u003c/p\u003e \u003cp\u003eWe used Cox proportional hazards regression to identify independent prognostic factors for RFS (and, in a parallel analysis, for OS). Each candidate variable (age group, sex, smoking status, ECOG, tumor size category, differentiation grade, histology, LVI, STAS, pleural invasion, surgical extent, and adjuvant chemotherapy) was first tested in univariate Cox models. Variables with \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.10 in univariate analysis were considered for inclusion in multivariable models. For the overall cohort, a stepwise multivariable Cox model was constructed to determine independent predictors of RFS. Given the limited sample size in the \u0026ge;\u0026thinsp;75 subgroup (\u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;51), we built a focused multivariable model for that subgroup including the key variables of interest (surgical extent and tumor size) and any other covariates that showed a suggestive association in univariate analysis. Hazard ratios (HR) with 95% confidence intervals (CI) were calculated for each factor.\u003c/p\u003e \u003cp\u003e \u003cb\u003ePropensity Score\u0026ndash;Matched Analysis\u003c/b\u003e: To further account for confounding differences between older and younger patients, we performed a propensity score matching analysis. Patients aged\u0026thinsp;\u0026ge;\u0026thinsp;75 were matched 1:1 to patients\u0026thinsp;\u0026lt;\u0026thinsp;75 based on baseline factors including pathologic stage (IA vs. IB), sex, ECOG performance status, and smoking history. Nearest-neighbor matching without replacement was applied (a caliper of 0.2 standard deviations was tested but ultimately not used, as it reduced balance in some covariates). This yielded 51 matched pairs (102 patients) with well-balanced covariates. Outcomes (RFS and OS) were then compared between the matched\u0026thinsp;\u0026ge;\u0026thinsp;75 and \u0026lt;\u0026thinsp;75 groups, effectively isolating the impact of age on outcomes under similar tumor and health conditions. We also explored the impact of surgical extent within each age stratum. Due to the smaller sample, a separate PSM within the \u0026ge;\u0026thinsp;75 group (matching lobectomy vs. sublobar patients) was not feasible; instead, we used multivariable adjustment in that subgroup to assess the effect of lobectomy vs. sublobar resection on RFS. Similarly, we examined lobectomy vs. sublobar outcomes in patients\u0026thinsp;\u0026lt;\u0026thinsp;75 for comparison.\u003c/p\u003e \u003cp\u003eAll statistical tests were two-sided, and \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant. Analyses were performed using SPSS v25 (IBM Corp) and R v4.0 (R Foundation for Statistical Computing). The study was approved by the institutional review boards of the participating hospitals, with a waiver of individual consent for deceased or lost patients given the retrospective design.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003ePatient Characteristics\u003c/h2\u003e \u003cp\u003eA total of 390 patients met the inclusion criteria for pathologic stage I NSCLC resection (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Of these, 51 patients (13.1%) were \u0026ge;\u0026thinsp;75 years (very elderly group), with a median age of 78 (range 75\u0026ndash;87), and the remaining 339 patients (86.9%) were \u0026lt;\u0026thinsp;75 years (younger group), median age 63 (range 32\u0026ndash;74). Baseline characteristics differed in a few notable ways between the age groups. Older patients were more likely to have a history of smoking (39.2% vs. 24.2% for \u0026lt;\u0026thinsp;75, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.03) and had a higher proportion of squamous cell carcinoma or other non-adenocarcinoma histology (15.7% of \u0026ge;\u0026thinsp;75 patients vs. 3.5% of \u0026lt;\u0026thinsp;75, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Pathologic stage IB (tumor\u0026thinsp;\u0026gt;\u0026thinsp;3 cm) was also more frequent in the \u0026ge;\u0026thinsp;75 group (54.9% vs. 35.1% in \u0026lt;\u0026thinsp;75, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.010), indicating that tumors tended to be larger in the elderly cohort despite similar inclusion criteria. In contrast, use of lobectomy vs. sublobar resection did not significantly differ by age \u0026ndash; in both groups approximately half of patients underwent lobectomy and half underwent sublobar resection (51.0% lobectomy in \u0026ge;\u0026thinsp;75 vs. 51.3% in \u0026lt;\u0026thinsp;75, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.00). This suggests surgeons did not uniformly favor a sublobar approach in the elderly, possibly reflecting careful case selection. Other variables such as sex distribution, ECOG performance status, and incidence of high-grade tumors or LVI were similar between age groups (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.1 for each), except for a trend toward higher STAS incidence in older patients (37.3% vs. 24.2%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.070). Adjuvant chemotherapy was administered to 11 of 51 older patients (21.6%) and 48 of 339 younger patients (14.2%); this difference was not statistically significant (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.24), indicating broadly comparable adjuvant treatment rates across ages.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline characteristics of the entire cohort (390 patients) stratified by age group. Values are given as number of patients (%) in each category.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;75\u0026nbsp;years\u0026nbsp;(N\u0026thinsp;=\u0026thinsp;339)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;75\u0026nbsp;years\u0026nbsp;(N\u0026thinsp;=\u0026thinsp;51)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e197 (58.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23 (45.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1105\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e142 (41.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28 (54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eECOG\u0026nbsp;performance status\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.2411\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e64 (18.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (13.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e271 (79.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42 (82.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u0026ndash;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4 (1.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2 (3.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSmoking history\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0352*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e257 (75.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e31 (60.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e82 (24.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20 (39.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eClinical stage\u003c/b\u003e\u0026nbsp;(pre-op)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.1307\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4 (1.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e278 (82.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38 (74.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e17 (5.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4 (7.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e21 (6.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (11.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e5 (1.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnknown\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e14 (4.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0 (0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOperation type\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.0000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLobectomy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e174 (51.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26 (51.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSublobar resection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e165 (48.7%)\u0026nbsp;\u0026dagger;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25 (49.0%)\u0026nbsp;\u0026dagger;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePathologic stage\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0103*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e220 (64.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23 (45.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e119 (35.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28 (54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTumor differentiation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.7087\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade\u0026nbsp;1\u0026ndash;2 (well/mod)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e247 (72.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39 (76.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade\u0026nbsp;3 (poor)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e92 (27.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12 (23.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistologic type\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0009***\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdenocarcinoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e327 (96.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e43 (84.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-adenocarcinoma\u0026nbsp;\u0026Dagger;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e12 (3.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (15.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLymphovascular invasion\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.8043\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e313 (92.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46 (90.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e26 (7.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5 (9.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSpread through air spaces\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0696\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e257 (75.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32 (62.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e82 (24.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e19 (37.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTumor size (largest diameter)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0019**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;20\u0026nbsp;mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e226 (66.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22 (43.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;20\u0026nbsp;mm and \u0026le;\u0026thinsp;40\u0026nbsp;mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e113 (33.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29 (56.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eVisceral pleural invasion\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0590\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePL0 (none)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e235 (69.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28 (54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePL1/PL2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e104 (30.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e23 (45.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAdjuvant chemotherapy\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.2431\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e291 (85.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e40 (78.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e48 (14.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (21.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05; ** \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01; *** \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001. \u0026dagger; \u0026ldquo;Sublobar\u0026rdquo; includes both wedge resection and segmentectomy. \u0026Dagger; Non-adenocarcinoma histologies in this series included squamous cell carcinoma, large cell carcinoma, pleomorphic carcinoma, lymphoepithelial carcinoma, basaloid squamous carcinoma, and adenosquamous carcinoma. ECOG: Eastern Cooperative Oncology Group performance status; LVI: lymphovascular invasion; STAS: spread through air spaces; PL: visceral pleural invasion.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003ePropensity Score\u0026ndash;Matched Analysis by Age\u003c/h2\u003e \u003cp\u003eTo ensure comparability of the two age groups, we performed a propensity score\u0026ndash;matched (PSM) analysis. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e summarizes baseline characteristics for the 51 matched pairs of older (\u0026ge;\u0026thinsp;75) and younger (\u0026lt;\u0026thinsp;75) patients after matching on sex, clinical stage, ECOG, and smoking history. As expected, the matching procedure eliminated most baseline differences. In the matched subset, there were no significant differences between the \u0026ge;\u0026thinsp;75 and \u0026lt;\u0026thinsp;75 groups in gender distribution, ECOG status, smoking history, clinical stage, or other tumor variables (all \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026gt;\u0026thinsp;0.2, except a borderline difference in differentiation grade). Standardized mean differences (SMD) for all matched covariates were below 0.1, indicating adequate balance. Notably, even in the matched groups, the proportion of lobectomy versus sublobar resection remained similar (51% vs. 58.8% lobectomy in \u0026ge;\u0026thinsp;75 and \u0026lt;\u0026thinsp;75, respectively, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.55), confirming that surgical extent was not heavily biased by age in our cohort. The only baseline variable with a suggestion of imbalance after matching was tumor differentiation: 76.5% of older patients had grade 1\u0026ndash;2 tumors vs. 58.8% of younger (p\u0026thinsp;=\u0026thinsp;0.090, SMD 0.377), though this did not reach significance. Overall, the PSM analysis indicates that the younger and very elderly patients in our study could be fairly compared, having similar baseline tumor stages and health status after matching.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline characteristics in the propensity score\u0026ndash;matched subset (51 pairs) of patients\u0026thinsp;\u0026lt;\u0026thinsp;75 vs. \u0026ge;75 years.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;75\u0026nbsp;years\u0026nbsp;(N\u0026thinsp;=\u0026thinsp;51)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ge;75\u0026nbsp;years\u0026nbsp;(N\u0026thinsp;=\u0026thinsp;51)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eSMD\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGender\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.0000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0390\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e22 (43.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23 (45.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29 (56.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e28 (54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eECOG status\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.8415\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.1160\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7 (13.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7 (13.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e43 (84.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e42 (82.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u0026ndash;3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1 (2.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2 (3.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSmoking history\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.0000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0400\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30 (58.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e31 (60.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e21 (41.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e20 (39.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eClinical stage\u003c/b\u003e\u0026nbsp;(pre-op)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9843\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0780\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e37 (72.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e38 (74.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4 (7.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4 (7.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6 (11.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6 (11.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e4 (7.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e3 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOperation type\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.5505\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.1580\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLobectomy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30 (58.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e26 (51.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSublobar resection\u0026nbsp;\u0026dagger;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e21 (41.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e25 (49.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePathologic stage\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.4283\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.1960\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e28 (54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23 (45.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIB\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e23 (45.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e28 (54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTumor differentiation\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.0904\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.3770\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade\u0026nbsp;1\u0026ndash;2 (well/mod)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30 (58.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e39 (76.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade\u0026nbsp;3 (poor)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e21 (41.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12 (23.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistologic type\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.2017\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.3160\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAdenocarcinoma\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e48 (94.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e43 (84.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNon-adenocarcinoma\u0026Dagger;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3 (5.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e8 (15.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLymphovascular invasion\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.0000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0630\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e45 (88.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e46 (90.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6 (11.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5 (9.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSpread through air spaces\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.6766\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.1240\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e35 (68.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e32 (62.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e16 (31.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e19 (37.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTumor size\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.0000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026le;20\u0026nbsp;mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e22 (43.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e22 (43.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;20\u0026nbsp;mm and \u0026le;\u0026thinsp;40\u0026nbsp;mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29 (56.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e29 (56.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eVisceral pleural invasion\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.0000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0390\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePL0 (none)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29 (56.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e28 (54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePL1/PL2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e22 (43.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23 (45.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAdjuvant chemotherapy\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.4359\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.2060\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e44 (86.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e40 (78.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e7\u0026nbsp;(13.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11 (21.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e\u0026dagger; \u0026ldquo;Sublobar\u0026rdquo; includes wedge resection and segmentectomy. \u0026Dagger; Non-adenocarcinoma histologies include those listed in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. No significant differences were observed after matching. SMD: standardized mean difference.\u003c/p\u003e \u003cp\u003eThe PSM results confirm that after matching, the older and younger cohorts were well balanced in terms of key baseline factors. This allowed for a fair comparison of outcomes by age, as described below.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSurvival Outcomes by Age Group\u003c/h3\u003e\n\u003cp\u003eWith a median follow-up of 63.7 months for surviving patients, oncologic outcomes were significantly worse in the very elderly group. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the Kaplan\u0026ndash;Meier RFS curves stratified by age. RFS \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA\u003cb\u003e)\u003c/b\u003e and OS \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB\u003cb\u003e)\u003c/b\u003e in patients\u0026thinsp;\u0026lt;\u0026thinsp;75 vs\u0026thinsp;\u0026ge;\u0026thinsp;75 years old with stage I NSCLC.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePatients\u0026thinsp;\u0026ge;\u0026thinsp;75 experienced a sharp drop in RFS in the first 2\u0026ndash;3 years after surgery. The 5-year RFS was only 64.7% in the \u0026ge;\u0026thinsp;75 group vs. 81.9% in the \u0026lt;\u0026thinsp;75 group (log-rank \u003cem\u003ep\u003c/em\u003e 0.0011). Overall survival was even more dramatically lower in the \u0026ge;\u0026thinsp;75 cohort: 5-year OS was 69.1% for \u0026ge;\u0026thinsp;75 vs. 91.5% for \u0026lt;\u0026thinsp;75 (log-rank \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). These differences remained significant even after accounting for baseline factors.\u003c/p\u003e \u003cp\u003e \u003cb\u003eRFS in patients\u0026thinsp;\u0026lt;\u0026thinsp;75 vs\u003c/b\u003e\u0026thinsp;\u0026ge;\u0026thinsp;\u003cb\u003e75 years old with stage I NSCLC (PSM).\u003c/b\u003e\u003c/p\u003e \u003cp\u003eIn the propensity-matched subset, age\u0026thinsp;\u0026ge;\u0026thinsp;75 was still associated with significantly worse RFS (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.042) \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003eA\u003cb\u003e)\u003c/b\u003e and markedly worse OS (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0024) \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003eB\u003cb\u003e).\u003c/b\u003e compared to \u0026lt;\u0026thinsp;75. In the matched analysis, 5-year RFS was approximately 64.7% in \u0026ge;\u0026thinsp;75 vs. 81.6% in \u0026lt;\u0026thinsp;75, and 5-year OS 69.1% vs. 91.8%, respectively. Thus, very advanced age itself emerged as a strong adverse prognostic factor for both recurrence and survival, even when controlling for tumor stage and health status.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eRisk Factors for Recurrence – Cox Regression Analysis (Overall Cohort after PSM)\u003c/h3\u003e\n\u003cp\u003eTo identify factors contributing to recurrence risk, we performed Cox proportional hazards analyses for RFS. In the multivariate Cox model \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e, age\u0026thinsp;\u0026ge;\u0026thinsp;75 years remained a significant independent predictor of worse RFS (HR 2.40, 95% CI 1.19\u0026ndash;4.84, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0146). In practical terms, even after adjusting for tumor factors, patients in the \u0026ge;\u0026thinsp;75 group had more than double the hazard of recurrence or death compared to those\u0026thinsp;\u0026lt;\u0026thinsp;75. Lymphovascular invasion (LVI) was another strong prognostic factor: patients with LVI-positive tumors had an almost five-fold higher hazard of recurrence (HR 4.64, 95% CI 1.69\u0026ndash;12.75, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0030) compared to those without LVI. \u003cb\u003eTumor size\u003c/b\u003e was also critical \u0026ndash; tumors\u0026thinsp;\u0026gt;\u0026thinsp;20 mm (within stage I, roughly corresponding to stage IB vs. IA) carried a significantly higher recurrence risk (HR 3.38, 95% CI 1.37\u0026ndash;8.31, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0081) than tumors\u0026thinsp;\u0026le;\u0026thinsp;20 mm. In contrast, \u003cb\u003esurgical extent (lobectomy vs. sublobar)\u003c/b\u003e was \u003cem\u003enot\u003c/em\u003e an independent predictor of RFS in the overall analysis (HR 1.61 for sublobar vs. lobectomy, 95% CI 0.83\u0026ndash;3.13, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.1570). This suggests that when all ages are considered together and other factors are controlled, choosing a sublobar resection did not significantly increase recurrence risk in the general stage I population. Other variables, such as tumor differentiation grade, histology, STAS, pleural invasion, and adjuvant chemotherapy, were not significant predictors of RFS in this multivariable model. Notably, adjuvant chemotherapy showed no clear benefit (HR 0.36, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.14 in multivariate analysis), consistent with its infrequent use and likely selection for higher-risk cases.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003e\u003cb\u003eCox proportional hazards analysis of recurrence-free survival (RFS) in stage I NSCLC (overall cohort) after propensity score matching.\u003c/b\u003e Both univariate and multivariate results are shown. Hazard ratios\u0026thinsp;\u0026gt;\u0026thinsp;1 indicate higher hazard of recurrence (worse RFS).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUnivariate HR (95%\u0026nbsp;CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUnivariate\u0026nbsp;\u003cem\u003ep value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMultivariate HR (95%\u0026nbsp;CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMultivariate\u003c/p\u003e \u003cp\u003e\u003cem\u003eP value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge group (\u0026ge;\u0026thinsp;75 vs. \u0026lt;75)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.17 (1.04\u0026ndash;4.52)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.0387*\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.40 (1.19\u0026ndash;4.84)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0146*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOperation type (sublobar vs. lobar)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.33 (0.69\u0026ndash;2.56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.3980\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.61 (0.83\u0026ndash;3.13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.1570\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDifferentiation (Grade\u0026nbsp;3 vs. 1\u0026ndash;2)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.75 (0.87\u0026ndash;3.54)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.1180\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistology (non-adenoca. vs. adeno)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.67 (0.63\u0026ndash;4.43)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.3040\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.30 (0.39\u0026ndash;4.30)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.6650\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLymphovascular invasion (Yes vs. No)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.88 (1.31\u0026ndash;6.31)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.0084**\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.64 (1.69\u0026ndash;12.75)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0030**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSpread through air spaces (Yes vs. No)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.60 (0.79\u0026ndash;3.23)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.1930\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTumor size (\u0026gt;\u0026thinsp;20\u0026nbsp;mm vs. \u0026le;20\u0026nbsp;mm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.17 (0.89\u0026ndash;5.27)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.0865\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.38 (1.37\u0026ndash;8.31)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0081**\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eVisceral pleural inv. (PL1/2 vs. PL0)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.06 (0.57\u0026ndash;1.94)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.8620\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAdjuvant chemotherapy (Yes vs. No)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.99 (0.38\u0026ndash;2.60)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.9840\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.36 (0.09\u0026ndash;1.39)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.1370\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05; ** \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.01. (Variables with \u0026ldquo;\u0026ndash;\u0026rdquo; in the multivariate columns were not included in the final multivariate model, as their univariate \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026ge;\u0026thinsp;0.10 or they were removed during model selection.) HR: hazard ratio; CI: confidence interval.\u003c/p\u003e \u003cp\u003eIn summary, for the overall stage I cohort, advanced age (\u0026ge;\u0026thinsp;75), presence of LVI, and larger tumor size were the dominant risk factors for recurrence, whereas the choice of lobectomy vs. sublobar resection was not a significant determinant of RFS when younger and older patients were analyzed together. This overall analysis, however, masks an important age interaction effect, as explored next.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eSubgroup Analysis: Very Elderly (\u0026ge;\u0026thinsp;75 Years) Patients\u003c/h2\u003e \u003cp\u003eGiven the stark differences in outcomes by age and our hypothesis that surgical extent might especially impact the very elderly, we conducted a subgroup analysis focusing on the 51 patients aged\u0026thinsp;\u0026ge;\u0026thinsp;75 years. We evaluated prognostic factors for RFS within this\u0026thinsp;\u0026ge;\u0026thinsp;75 group \u003cb\u003e(\u003c/b\u003eTable\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e and examined the effect of lobectomy vs. sublobar resection on outcomes in these patients. In univariate analysis among patients\u0026thinsp;\u0026ge;\u0026thinsp;75, some covariates showed notable effects on RFS, although the small sample limited statistical power. Most importantly, \u003cb\u003esurgical extent\u003c/b\u003e demonstrated a strong trend: sublobar resection had a 2.56-fold higher hazard of recurrence compared to lobectomy (HR 2.56, 95% CI 0.97\u0026ndash;6.76, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.057) in univariate analysis, narrowly missing conventional significance. After adjusting for tumor size and other factors in a multivariable Cox model, \u003cb\u003elimited resection emerged as a significant independent predictor of worse RFS\u003c/b\u003e (adjusted HR 3.57, 95% CI 1.02\u0026ndash;12.51, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0462). In other words, an elderly patient who underwent a sublobar resection had over \u003cb\u003e3.57 times higher risk of recurrence\u003c/b\u003e than a similar patient who had a lobectomy, when controlling for tumor size and pathology. This is a critical finding, indicating that in very elderly patients the extent of surgical resection significantly impacts oncologic outcomes, with lobectomy conferring superior long-term RFS.\u003c/p\u003e \u003cp\u003eOther factors in the \u0026ge;\u0026thinsp;75 subgroup analysis included tumor size, which was identified as an important prognostic factor despite a modest univariate effect. Patients with tumors\u0026thinsp;\u0026gt;\u0026thinsp;20 mm appeared to have worse RFS than those with \u0026le;\u0026thinsp;20 mm tumors (univariate HR 1.64, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.316, not significant). However, in the multivariate model that accounted for surgical extent and other variables, tumor size\u0026thinsp;\u0026gt;\u0026thinsp;2 cm became a significant independent predictor of shorter RFS (adjusted HR 3.41, 95% CI 1.16\u0026ndash;10.0, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.0256). Thus, in very elderly patients, having a tumor larger than 2 cm was associated with a more than three-fold higher hazard of recurrence, after adjusting for surgery type and other factors.\u003c/p\u003e \u003cp\u003eBy contrast, many pathological features that were prognostic in the overall cohort did not significantly stratify the \u0026ge;\u0026thinsp;75 patients. For example, LVI, STAS, and poor differentiation did not show an association with higher recurrence in the elderly group (indeed, the hazard ratios for LVI and STAS were \u0026lt;\u0026thinsp;1 in this subgroup, albeit with wide confidence intervals and non-significant \u003cem\u003ep\u003c/em\u003e-values). This suggests that the adverse impact of these features was attenuated in very elderly patients, possibly due to the overriding influence of other factors or simply limited sample size. Patient sex, smoking history, and ECOG performance status were also not significantly associated with RFS in \u0026ge;\u0026thinsp;75 patients.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCox proportional hazards analysis of recurrence-free survival (RFS) in very elderly patients (\u0026ge;\u0026thinsp;75 years, \u003cem\u003en\u003c/em\u003e\u0026thinsp;=\u0026thinsp;51). The multivariate model for this subgroup included surgical extent and tumor size, as well as other covariates of interest.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUnivariate HR (95%\u0026nbsp;CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eUnivariate\u003c/p\u003e \u003cp\u003e\u003cem\u003eP value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMultivariate HR\u003c/p\u003e \u003cp\u003e(95%\u0026nbsp;CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMultivariate\u003c/p\u003e \u003cp\u003e\u003cem\u003eP value\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eGender (Male vs. Female)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.64 (0.65\u0026ndash;4.18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.2970\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSmoking history (Yes vs. No)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.20 (0.48\u0026ndash;2.99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.6960\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eECOG (1 vs. 0)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.56 (0.18\u0026ndash;1.71)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.3090\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eECOG (2\u0026ndash;3 vs. 0)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.26 (0.14\u0026ndash;11.46)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.8360\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eOperation type (sublobar vs. lobar)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.56 (0.97\u0026ndash;6.76)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.0568\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.57 (1.02\u0026ndash;12.51)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0462*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHistology (non-adenoca. vs. adeno)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.11 (0.32\u0026ndash;3.82)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.8660\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.26 (0.50\u0026ndash;10.19)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.2880\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDifferentiation (Grade\u0026nbsp;3 vs. 1\u0026ndash;2)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.77 (0.25\u0026ndash;2.31)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.6360\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLymphovascular invasion (Yes vs. No)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.56 (0.07\u0026ndash;4.21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.5720\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSpread through air spaces (Yes vs. No)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.80 (0.31\u0026ndash;2.03)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.6390\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026ndash;\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eTumor size (\u0026gt;\u0026thinsp;20\u0026nbsp;mm vs. \u0026le;20\u0026nbsp;mm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1.64 (0.62\u0026ndash;4.34)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.3160\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.41 (1.16\u0026ndash;10.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.0256*\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eVisceral pleural inv. (PL1/2 vs. PL0)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.46 (0.18\u0026ndash;1.22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.1210\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.45 (0.16\u0026ndash;1.28)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.1360\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAdjuvant chemotherapy (Yes vs. No)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.61 (0.18\u0026ndash;2.11)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.4370\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.67 (0.17\u0026ndash;2.67)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.5730\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05. HR: hazard ratio; CI: confidence interval. (Univariate HRs are not shown for reference categories such as ECOG 0, lobectomy, etc. Multivariate model included surgical extent, tumor size, histology, pleural invasion, and chemotherapy; other variables were not included due to non-significance or model parsimony.)\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThis analysis highlights that in our very elderly cohort, the extent of resection and tumor size were the primary drivers of recurrence risk, whereas other tumor features played a lesser role.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eSurgical Extent and Recurrence-Free Survival in very elderly patients\u003c/h2\u003e \u003cp\u003eTo illustrate the impact of surgical extent on outcomes in both age groups, we plotted Kaplan\u0026ndash;Meier RFS curves for lobectomy versus sublobar resection \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAmong the 51 very elderly patients (\u0026ge;\u0026thinsp;75 years), 26 underwent lobectomy and 25 underwent sublobar resection. The RFS curves separated distinctly between these subgroups. At 5 years post-surgery, RFS was 76.6% for patients who underwent lobectomy compared with 50.8% for those who had sublobar resection (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.048). Most recurrences in the elderly sublobar group occurred within the first 2\u0026ndash;3 years, whereas the lobectomy group\u0026rsquo;s RFS curve plateaued at a higher level, indicating superior long-term cancer control with lobectomy.\u003c/p\u003e \u003cp\u003eThe finding reinforce that, in very elderly patients, a full lobar resection provides a measurable oncologic benefit in preventing recurrence compared with limited resection.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eTumor Size and Recurrence-Free Survival in the Elderly\u003c/h2\u003e \u003cp\u003eBeyond surgical extent, tumor size emerged as a critical prognostic factor in the very elderly in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWithin stage I disease, a cutoff of 2 cm, delineated distinct risk strata. In the \u0026ge;\u0026thinsp;75-year cohort, tumors larger than 2 cm were independently associated with shorter RFS in multivariable Cox analysis (HR 3.41, 95% CI 1.16\u0026ndash;10.0, p\u0026thinsp;=\u0026thinsp;0.026; Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Although the difference in absolute 5-year RFS did not reach statistical significance (55% vs 80.6%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.31; Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003e), a clear trend toward poorer outcomes with increasing tumor size was observed.\u003c/p\u003e \u003cp\u003eThe adverse effect of larger tumor size was particularly evident when combined with limited resection. Among elderly patients with tumors\u0026thinsp;\u0026gt;\u0026thinsp;2 cm, sublobar resection was associated with the highest recurrence risk, whereas lobectomy may mitigate much of this size-related disadvantage. Conversely, for tumors\u0026thinsp;\u0026le;\u0026thinsp;2 cm, sublobar resection yielded relatively acceptable disease control\u0026mdash;albeit in a smaller subset\u0026mdash;consistent with the notion that small, peripheral tumors may be adequately managed with anatomical segmentectomy when lobectomy is not feasible. These findings reinforce the importance of integrating tumor size and physiological fitness into individualized surgical planning for very elderly patients with stage I NSCLC.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003ePostoperative Chemotherapy in the Elderly\u003c/h2\u003e \u003cp\u003eAmong the very elderly cohort, only 11 patients received adjuvant chemotherapy, while 40 did not. At 5 years after surgery, RFS was 72.7% in patients who received chemotherapy compared with 62.3% in those who did not (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.43) in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eOther Prognostic Factors in the Elderly\u003c/h2\u003e \u003cp\u003eOther pathological factors did not significantly stratify recurrence risk in the \u0026ge;\u0026thinsp;75 group. Poor differentiation, LVI, STAS, and visceral pleural invasion, which were adverse features in the overall cohort, showed attenuated or no effect in the elderly cohort.\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study examined outcomes in very elderly patients (\u0026ge;\u0026thinsp;75 years) with pathologic stage I NSCLC and demonstrated that surgical extent strongly influenced recurrence-free survival (RFS). In this population, lobectomy was associated with significantly superior recurrence control compared with sublobar resection, whereas this effect was not observed in patients younger than 75 years. These findings underscore that, although sublobar resection has been validated as oncologically adequate in selected younger patients with small tumors, its effectiveness may be diminished in very elderly patients.\u003c/p\u003e \u003cp\u003eOur results extend prior randomized evidence from CALGB 140503 and JCOG0802, which demonstrated the non-inferiority of sublobar resection for tumors\u0026thinsp;\u0026le;\u0026thinsp;2 cm in predominantly younger cohorts[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Importantly, these landmark trials included few patients\u0026thinsp;\u0026ge;\u0026thinsp;75 years, limiting their applicability to this population. The present study suggests that age may modify the oncologic adequacy of sublobar resection. One plausible explanation is that wedge resections are more frequently performed in elderly patients due to frailty or impaired pulmonary reserve. Wedge resections, lacking anatomical precision and comprehensive nodal evaluation, are consistently associated with higher local recurrence rates compared with segmentectomy[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. This likely contributed to the inferior outcomes observed in elderly patients who underwent sublobar resection.\u003c/p\u003e \u003cp\u003eSeveral pathological features were prognostic for shorter RFS in the overall stage I lung cancer cohort but did not significantly stratify recurrence risk in patients aged\u0026thinsp;\u0026ge;\u0026thinsp;75 years. Poor differentiation, lymphovascular invasion (LVI), spread through air spaces (STAS), and visceral pleural invasion\u0026mdash;all adverse factors in the younger population[\u003cspan additionalcitationids=\"CR21\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u0026mdash;showed attenuated or no effect in the very elderly. This attenuation may reflect limited statistical power due to the smaller sample size, or it may represent a true biological difference, such as inherently less aggressive tumor behavior in the very elderly or the predominance of competing non-cancer risks that overshadow the prognostic impact of tumor-related factors.\u003c/p\u003e \u003cp\u003eAnother critical factor is the limited role of adjuvant chemotherapy in the very elderly. Published studies have suggested that adjuvant chemotherapy can improve prognosis after standard lung cancer surgery, even in patients over 75 years with early-stage NSCLC[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. However, in our cohort, only a minority of patients\u0026thinsp;\u0026ge;\u0026thinsp;75 years received systemic therapy. As a result, microscopic residual disease following limited resection was seldom addressed, in contrast to younger patients where adjuvant treatment may partially mitigate oncologic risk. This underscores the importance of achieving complete oncologic clearance through surgery in elderly patients, for whom systemic therapy is often not feasible.\u003c/p\u003e \u003cp\u003eNotably, advanced age itself remained an independent predictor of recurrence, even after adjusting for tumor size and pathologic risk factors. This observation suggests that host-related factors such as immunosenescence, frailty, or diminished physiologic reserve may impair the ability to suppress micrometastatic disease. Thus, in very elderly patients, optimal surgical clearance may be particularly critical[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Our subgroup analysis further showed that tumor size\u0026thinsp;\u0026gt;\u0026thinsp;2 cm independently predicted recurrence, especially when combined with limited resection. These findings reinforce that lobectomy should remain the preferred strategy for physiologically fit elderly patients, particularly for larger tumors. Indeed, elderly patients who underwent lobectomy in our study achieved RFS comparable to that of younger lobectomy patients, and this was accomplished without evidence of increased perioperative mortality.\u003c/p\u003e \u003cp\u003eFor patients unable to tolerate lobectomy, anatomic segmentectomy may represent a reasonable alternative, as it provides superior margins and nodal assessment compared with wedge resection[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. However, wedge resections should be reserved for patients with prohibitive operative risks. For those deemed unfit for any surgery, stereotactic body radiotherapy (SBRT) remains an important alternative method[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOur findings are consistent with prior elderly-specific investigations. For instance, Chen et al. demonstrated that lobectomy conferred a survival advantage over sublobar resection in patients\u0026thinsp;\u0026ge;\u0026thinsp;75 years with stage I adenocarcinoma\u0026thinsp;\u0026le;\u0026thinsp;3 cm[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], supporting the conclusion that more extensive resection improves cancer control in the elderly. Conversely, SEER database analyses and meta-analyses have suggested no survival difference between lobectomy and sublobar resection in elderly patients, but these studies primarily assessed overall survival (OS), which may be confounded by competing non-cancer mortality[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. By focusing on RFS, our study provides clearer evidence that cancer control is indeed compromised by sublobar resection in very elderly patients, even if OS appears similar due to competing risks.\u003c/p\u003e \u003cp\u003eSeveral limitations warrant consideration. First, this was a retrospective, two-institutional analysis with a relatively small number of patients\u0026thinsp;\u0026ge;\u0026thinsp;75 years (13% of the cohort), which may limit generalizability and statistical power. Second, the \u0026ldquo;sublobar\u0026rdquo; group combined segmentectomy and wedge resection, which are not oncologically equivalent. Although small sample size precluded separate analyses, it is likely that the higher recurrence risk was driven primarily by wedge resections. Third, detailed information on pulmonary function and frailty indices was not consistently available; thus, unmeasured confounding related to operative selection cannot be excluded. Nevertheless, the fact that recurrence\u0026mdash;not only OS\u0026mdash;was significantly higher in elderly patients undergoing sublobar resection suggests a true oncologic disadvantage rather than survival bias alone.\u003c/p\u003e \u003cp\u003eIn conclusion, our study demonstrates that lobectomy provides superior recurrence control compared with sublobar resection in very elderly patients with stage I NSCLC, particularly for tumors\u0026thinsp;\u0026gt;\u0026thinsp;2 cm, without evidence of increased perioperative risk. These findings support lobectomy as the preferred surgical approach for fit elderly patients whenever feasible. For patients unable to tolerate lobectomy, anatomic segmentectomy is preferable to wedge resection. Future prospective studies focusing specifically on patients\u0026thinsp;\u0026ge;\u0026thinsp;75 years are needed to confirm these results and to refine surgical guidelines for this growing patient population.\u003c/p\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCRediT authorship contribution statement\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceptualization: Chih-Jen Yang, Jen-Yu Hung, Inn-Wen Chong, Jui-Ying Lee; Data collection : Yu-Ting Lo, Yu-Wei Liu, Tai-Huang Lee, Hui-Yang Hung, Cheng-Hao Chuang, Wei-An Lai ; Data analysis and interpretation of results : Yi-Wen Shen, Shih-Yu Kao. Draft manuscript preparation: Jui-Ying Lee, Min-Fang Chao, Inn-Wen Chong, Chih-Jen Yang; All authors reviewed the results and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u0026nbsp;\u003c/strong\u003enone\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability:\u0026nbsp;\u003c/strong\u003eThe datasets used and/or analyzed are available from the corresponding author on reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication:\u0026nbsp;\u003c/strong\u003eNot applicable.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u0026nbsp;\u003c/strong\u003eThe study was conducted in accordance with the Declaration of Helsinki, and approved by the Institutional Review Board of Kaohsiung Medical University Hospital (KMUH) (KMUHIRB-E(I)-20240126)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number:\u0026nbsp;\u003c/strong\u003enot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank staff members of the Cancer Center, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eThai AA, Solomon BJ, Sequist LV, Gainor JF, Heist RS. Lung cancer. Lancet. 2021;398(10299):535\u0026ndash;54.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNational Lung Screening Trial, Research T, Aberle DR, Adams AM, Berg CD, Black WC, Clapp JD, Fagerstrom RM, Gareen IF, Gatsonis C, Marcus PM, et al. Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med. 2011;365(5):395\u0026ndash;409.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen CL, Hsu JS, Shen YW, Hsu CH, Kao SY, Lai WA, Chuang CH, Liu YW, Lee JY, Chou SH et al. Changes in Staging and Management of Non-Small Cell Lung Cancer (NSCLC) Patients Following the Implementation of Low-Dose Chest Computed Tomography (LDCT) Screening at Kaohsiung Medical University Hospital. \u003cem\u003eCancers (Basel)\u003c/em\u003e 2024, 16(22).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYang CY, Lin YT, Lin LJ, Chang YH, Chen HY, Wang YP, Shih JY, Yu CJ, Yang PC. Stage Shift Improves Lung Cancer Survival: Real-World Evidence. J Thorac Oncol. 2023;18(1):47\u0026ndash;56.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChang GC, Chiu CH, Yu CJ, Chang YC, Chang YH, Hsu KH, Wu YC, Chen CY, Hsu HH, Wu MT, et al. Low-dose CT screening among never-smokers with or without a family history of lung cancer in Taiwan: a prospective cohort study. Lancet Respir Med. 2024;12(2):141\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLu G, Xiang Z, Zhou Y, Dai S, Tong F, Jiang R, Dai M, Zhang Q, Zhang D. Comparison of lobectomy and sublobar resection for stage I non-small cell lung cancer: a meta-analysis based on randomized controlled trials. Front Oncol. 2023;13:1261263.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRudasill S, Farjah F. Surgical Therapy for Stage I Lung Cancer-Lobar Versus Sublobar Resection. Semin Respir Crit Care Med 2025.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBravo-Iniguez C, Perez Martinez M, Armstrong KW, Jaklitsch MT. Surgical resection of lung cancer in the elderly. Thorac Surg Clin. 2014;24(4):371\u0026ndash;81.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen C, Ni Q, Shi Y, Fu S, Pan X, Wang Y, Yang J, Wang R. Prognosis analysis of lobectomy and sublobar resection in patients \u0026gt;/=75 years old with pathological stage I invasive lung adenocarcinoma of =3 cm: a propensity score matching-based analysis\u0026lt;/at. Transl Cancer Res. 2019;8(2):574\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDong S, Roberts SA, Chen S, Zhong X, Yang S, Qu X, Xu S. Survival after lobectomy versus sub-lobar resection in elderly with stage I NSCLC: a meta-analysis. BMC Surg. 2019;19(1):38.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAltorki N, Wang X, Kozono D, Watt C, Landrenau R, Wigle D, Port J, Jones DR, Conti M, Ashrafi AS, et al. Lobar or Sublobar Resection for Peripheral Stage IA Non-Small-Cell Lung Cancer. N Engl J Med. 2023;388(6):489\u0026ndash;98.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaji H, Okada M, Tsuboi M, Nakajima R, Suzuki K, Aokage K, Aoki T, Okami J, Yoshino I, Ito H, et al. Segmentectomy versus lobectomy in small-sized peripheral non-small-cell lung cancer (JCOG0802/WJOG4607L): a multicentre, open-label, phase 3, randomised, controlled, non-inferiority trial. Lancet. 2022;399(10335):1607\u0026ndash;17.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRazi SS, John MM, Sainathan S, Stavropoulos C. Sublobar resection is equivalent to lobectomy for T1a non-small cell lung cancer in the elderly: a Surveillance, Epidemiology, and End Results database analysis. J Surg Res. 2016;200(2):683\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Y, Yuan C, Zhang Y, Sun Y, Chen H. Survival following segmentectomy or lobectomy in elderly patients with early-stage lung cancer. Oncotarget. 2016;7(14):19081\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang Z, Feng H, Xiao F, Liu D. Limited resection in clinical stage I non-small cell lung cancer patients aged 75 years old or more: a meta-analysis. Ann Transl Med. 2018;6(18):359.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi Y, Hu S, Xie J, Zhang X, Zong Y, Xu B, Li C. Effects of surgery on survival of elderly patients with stage I small-cell lung cancer: analysis of the SEER database. J Cancer Res Clin Oncol. 2019;145(9):2397\u0026ndash;404.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNg J, Masuda Y, Ng JJ, Leow L, Choong A, Mithiran H. Lobar versus Sublobar Resection in the Elderly for Early Lung Cancer: A Meta-Analysis. Thorac Cardiovasc Surg. 2022;70(3):217\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHattori A, Suzuki K, Takamochi K, Wakabayashi M, Sekino Y, Tsutani Y, Nakajima R, Aokage K, Saji H, Tsuboi M, et al. Segmentectomy versus lobectomy in small-sized peripheral non-small-cell lung cancer with radiologically pure-solid appearance in Japan (JCOG0802/WJOG4607L): a post-hoc supplemental analysis of a multicentre, open-label, phase 3 trial. Lancet Respir Med. 2024;12(2):105\u0026ndash;16.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang P, Wang S, Liu Z, Sui X, Wang X, Li X, Qiu M, Yang F. Segmentectomy and Wedge Resection for Elderly Patients with Stage I Non-Small Cell Lung Cancer: A Systematic Review and Meta-Analysis. J Clin Med 2022, 11(2).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNakagawa K, Watanabe SI, Wakabayashi M, Yotsukura M, Mimae T, Hattori A, Miyoshi T, Isaka M, Endo M, Yoshioka H, et al. Risk Factors for Locoregional Relapse After Segmentectomy: Supplementary Analysis of the JCOG0802/WJOG4607L Trial. J Thorac Oncol. 2025;20(2):157\u0026ndash;66.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFick CN, Dunne EG, Vanstraelen S, Toumbacaris N, Tan KS, Rocco G, Molena D, Huang J, Park BJ, Rekhtman N, et al. High-risk features associated with recurrence in stage I lung adenocarcinoma. J Thorac Cardiovasc Surg. 2025;169(2):436\u0026ndash;44. e436.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChuang CH, Liu YW, Lai WA, Shen YW, Kao SY, Wei YC, Chien CC, Hung HY, Lee JY, Chao MF et al. Impact of Spread Through Air Spaces (STAS) on Recurrence and Surgical Trends in Stage I Non-Small Cell Lung Cancer: A Real-World Cohort Study. Kaohsiung J Med Sci 2025:e70061.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYamanashi K, Okumura N, Yamamoto Y, Takahashi A, Nakashima T, Matsuoka T, Kameyama K. Adjuvant chemotherapy for elderly patients with non-small-cell lung cancer. Asian Cardiovasc Thorac Ann. 2017;25(5):371\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSantos FN, de Castria TB, Cruz MR, Riera R. Chemotherapy for advanced non-small cell lung cancer in the elderly population. Cochrane Database Syst Rev. 2015;2015(10):CD010463.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShinde A, Li R, Kim J, Salgia R, Hurria A, Amini A. Stereotactic body radiation therapy (SBRT) for early-stage lung cancer in the elderly. Semin Oncol. 2018;45(4):210\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKreinbrink P, Blumenfeld P, Tolekidis G, Sen N, Sher D, Marwaha G. Lung stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer in the very elderly (\u0026gt;/=80years old): Extremely safe and effective. J Geriatr Oncol. 2017;8(5):351\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-pulmonary-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pulm","sideBox":"Learn more about [BMC Pulmonary Medicine](http://bmcpulmmed.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pulm/default.aspx","title":"BMC Pulmonary Medicine","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"surgical intervention, stage I lung cancer, elderly","lastPublishedDoi":"10.21203/rs.3.rs-8301020/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8301020/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThe optimal surgical strategy for very elderly patients (\u0026ge;\u0026thinsp;75 years) with stage I non\u0026ndash;small cell lung cancer (NSCLC) remains uncertain.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe retrospectively analyzed 390 patients with pathologic stage I NSCLC (\u0026le;\u0026thinsp;4 cm, N0) who underwent curative resection at two university-affiliated hospitals. Fifty-one patients were aged\u0026thinsp;\u0026ge;\u0026thinsp;75 years and 339 were \u0026lt;\u0026thinsp;75 years. Recurrence-free survival (RFS) was the primary endpoint, and overall survival (OS) was secondary. Propensity-score matching (PSM) balanced baseline factors, and multivariable Cox regression identified independent predictors of recurrence.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOlder patients had significantly worse outcomes than younger ones (5-year RFS 65% vs. 82%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001; OS 69% vs. 92%, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). After PSM, age\u0026thinsp;\u0026ge;\u0026thinsp;75 remained an independent predictor of recurrence (HR 2.40, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.015) and overall survival (HR 4.40, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001). In the very elderly subgroup, lobectomy provided superior recurrence control compared with sublobar resection (5-year RFS 76.6% vs. 50.8%; HR 3.57, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.046). Tumor size\u0026thinsp;\u0026gt;\u0026thinsp;2 cm also predicted poorer RFS (HR 3.41, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.026). High-risk pathological features (poor differentiation, LVI, STAS) were predictive in the overall cohort but less so in the very elderly. Adjuvant chemotherapy had no significant effect on RFS.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eIn very elderly patients with stage I NSCLC, tumor size and surgical extent were the main predictors of recurrence. Lobectomy achieved superior recurrence-free survival, underscoring the importance of optimal oncologic clearance during initial surgery when adjuvant therapy is rarely feasible.\u003c/p\u003e","manuscriptTitle":"Surgical Strategy and Prognostic Factors in Very Elderly (≥75 Years) Patients with Stage I NSCLC: Insights From a Propensity Score–Matched Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-20 11:35:56","doi":"10.21203/rs.3.rs-8301020/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-11T07:39:34+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-09T15:51:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-30T06:53:53+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-22T17:06:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"99706547144492448686739951382581230540","date":"2026-01-22T13:38:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"164529958208214970288858645594748663308","date":"2026-01-21T00:49:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"180723864226795199776899498222941531727","date":"2026-01-19T10:39:40+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-16T00:11:26+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-01-01T18:39:55+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-12-10T16:05:52+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-12-10T16:00:14+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pulmonary Medicine","date":"2025-12-10T15:49:33+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pulmonary-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"pulm","sideBox":"Learn more about [BMC Pulmonary Medicine](http://bmcpulmmed.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/pulm/default.aspx","title":"BMC Pulmonary Medicine","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"b938f8ce-822d-4bac-9d3a-521ab0dd9d91","owner":[],"postedDate":"January 20th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2026-04-13T16:04:06+00:00","versionOfRecord":{"articleIdentity":"rs-8301020","link":"https://doi.org/10.1186/s12890-026-04265-4","journal":{"identity":"bmc-pulmonary-medicine","isVorOnly":false,"title":"BMC Pulmonary Medicine"},"publishedOn":"2026-04-07 15:57:53","publishedOnDateReadable":"April 7th, 2026"},"versionCreatedAt":"2026-01-20 11:35:56","video":"","vorDoi":"10.1186/s12890-026-04265-4","vorDoiUrl":"https://doi.org/10.1186/s12890-026-04265-4","workflowStages":[]},"version":"v1","identity":"rs-8301020","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8301020","identity":"rs-8301020","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}