Assessment of the necessity of interlobar lymph node dissection in pathological stage IB non-small cell lung cancer: a propensity score-matched study

Assessment of the necessity of interlobar lymph node dissection in pathological stage IB non-small cell lung cancer: a propensity score-matched study | 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 Assessment of the necessity of interlobar lymph node dissection in pathological stage IB non-small cell lung cancer: a propensity score-matched study Hao Chen, Dongjie Yan, Chunming Liu, Lanjun Zhang, Yi Han, Feng Wang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8433359/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Lung cancer is the leading cause of cancer-related deaths worldwide, with non-small cell lung cancer (NSCLC) being the most common type. Systematic lymph node dissection (SLND) is a standard procedure for NSCLC, but the necessity of routine interlobar lymph node dissection (ILND) in early-stage disease, particularly in stage IB NSCLC, remains debated. While ILND can be technically performed, its benefit in improving overall survival (OS) or recurrence-free survival (RFS) is unclear. The need for routine ILND remains controversial, with limited studies addressing its role in early-stage disease. This study aimed to assess whether ILND contributes to better survival outcomes in stage IB NSCLC. Methods We retrospectively analyzed 597 IB-stage NSCLC patients who underwent radical surgery for lung cancer at Sun Yat-Sen University Cancer Center from 1999 to 2009. We used the Cox proportional hazards regression model to analyze prognostic factors. After propensity-score matching (PSM), 458 patients were selected. We applied the Kaplan-Meier method and log-rank test to compare OS and RFS. Results Among 597 patients included in the study, 262 did not have ILND, while 335 did. According to whether the interlobar lymph nodes were dissected, 597 patients were divided into two groups. Significant differences were found between the two groups in laterality, number of dissected lymph node stations, and number of dissected lymph nodes (P < 0.05). Univariate and multivariate Cox analyses by the Cox proportional hazards model showed that age, family history of malignant tumors, and number of dissected lymph nodes were prognostic factors for OS (P < 0.05). For RFS, age and number of dissected lymph nodes were significant (P 0.05). Conclusion In stage IB NSCLC patients, ILND is not significantly associated with OS or RFS. Routine ILND is not necessary for early-stage NSCLC. Non-small cell lung cancer (NSCLC) Propensity score matching (PSM) Interlobar lymph nodes Overall survival (OS) Recurrence-free survival (RFS) Figures Figure 1 Figure 2 Figure 3 Figure 4 Background Lung cancer is the leading cause of cancer-related deaths worldwide, with non-small cell lung cancer (NSCLC) accounting for the predominant proportion[ 1 ]. Since Cahan first reported 48 cases of radical lobectomy in 1960, this surgical procedure has gradually become the standard of surgical treatment for lung cancer[ 2 ]. Lymph node (LN) metastasis is a critical predictor of prognosis in NSCLC[ 3 ]. Currently, systematic lymph node dissection (SLND) is recognized as a key tool to provide more accurate tumor staging and improve patient survival by removing potential micrometastases[ 4 ]. With the development of surgical techniques, including robot-assisted thoracoscopic surgery (RATS) and video-assisted thoracoscopic surgery (VATS), the visualization of lymph node regions has been significantly enhanced[ 5 , 6 ]. The difficulty of systematic lymph node dissection has been significantly reduced. However, excessive lymph node dissection may elevate the risk of postoperative complications, such as hemorrhage, chylothorax, cardiovascular disease and nerve injury[ 7 – 10 ]. Furthermore, in the case of lung surgery, studies have shown that longer surgical duration is linked to higher mortality risk[ 11 ]. Systematic mediastinal lymphadenectomy (SMLD) inevitably prolongs the duration of surgery, which in turn increases the risk of such complications[ 12 ]. In summary, how to ensure accurate tumor staging while selecting the most appropriate lymph node dissection scope and minimizing surgical trauma remains a central challenge in clinical practice. Systematic lymph node dissection (SLND) has long been a cornerstone in the surgical management of NSCLC, supported by a body of robust clinical evidence that underscores its role in improving 5-year survival rates, particularly in early-stage disease. However, recent studies have questioned the necessity of SLND, particularly in patients with clinically lymph node-negative (cN0) disease. These studies indicate that lobe-specific systematic nodal dissection (L-SND) may yield comparable oncological outcomes to conventional SLND. Interlobar lymph nodes are located in the lung parenchyma between lobar and segmental bronchi and occupy concealed anatomical positions adjacent to pulmonary lobes. These lymph nodes are surrounded by critical structures, including pulmonary arteries, veins and bronchi. The narrow surgical field in this region significantly increases procedural complexity. SLND should include stations 2R, 4R, 7, 8 and 9 for right-sided cancers and stations 4L, 5, 6, 7, 8 and 9 for left-sided lung cancers[ 13 ]. However, the necessity of routine dissection of these lymph nodes remains controversial[ 14 , 15 ]. By now, there are no studies on the necessity of dissection of interlobar lymph nodes in patients with stage IB NSCLC. In this study, we aimed to evaluate the impact of ILND on survival outcomes in patients with stage IB NSCLC. Given the aforementioned controversies, this study aims to evaluate the survival benefits of ILND in patients with stage IB NSCLC and to provide evidence-based guidance for optimizing surgical strategies in early-stage NSCLC. Methods Patients and Study Design Between January 1999 and December 2009, clinical data were retrospectively collected from patients with NSCLC who underwent radical lung cancer surgery at Sun Yat-Sen University Cancer Center. The inclusion criteria were as follows: i) pathologically confirmed NSCLC; ii) pathological stage IB disease; and iii) no history of neoadjuvant therapy prior to surgery. All cases were re-staged according to the 8th edition of the IASLC/AJCC TNM classification based on pathological tumor size and lymph node status. All pathological diagnoses were independently confirmed by two experienced pathologists. The exclusion criteria were: i) incomplete or missing lymph node information; ii) presence of severe cardiovascular disease, autoimmune disease or active preoperative infection; and iii) lack of complete follow-up data. After applying these criteria, a total of 597 patients with pathological stage IB NSCLC were included in the present study. Follow-up After surgery, patients were monitored according to a structured schedule: every 3 months for the first 2 years, every 6 months between years 3 and 5, and once per year thereafter. At each visit, clinical examination, routine laboratory testing, serum tumor marker assessment, chest computed tomography and abdominal ultrasonography were performed. Brain magnetic resonance imaging was arranged annually, or earlier if neurological symptoms or other clinical suspicion arose. Overall survival (OS) was calculated from the date of resection to death from any cause or last contact. Recurrence-free survival (RFS) was measured from the date of surgery to the earliest of locoregional or distant relapse, or death from any cause; patients without an event were censored at their last recorded follow-up. The follow-up period was closed in January 2013. Surgical procedures and postoperative management All patients underwent comprehensive preoperative assessment to exclude surgical contraindications. Treatment strategies were determined by a multidisciplinary team, and anatomical pulmonary resection was recommended for patients deemed suitable for surgery. Lobectomy or more extensive anatomical resection was performed in all cases. Systematic lymph node dissection (SLND) was carried out in accordance with contemporary guideline-based practice. For right-sided tumors, lymphadenectomy generally included stations 2R, 4R, 7, 8 and 9, whereas for left-sided tumors, stations 4L, 5, 6, 7, 8 and 9 were routinely dissected. ILND was defined as the removal of station 11 lymph nodes located in the interlobar region between adjacent pulmonary lobes. Whether ILND was performed was determined by the operating surgeon, based on intraoperative findings and anatomical considerations. Postoperative adjuvant chemotherapy was administered according to prevailing clinical practice guidelines and individual patient risk profiles, particularly in those with high-risk pathological features. Statistical analysis Categorical data were described as counts with corresponding percentages and were compared between the ILND and non-ILND groups using the χ² test or Fisher’s exact test when appropriate. Continuous variables were presented as mean ± standard deviation or as median with interquartile range, and group differences were evaluated with the student’s t-test or Mann–Whitney U test according to the distribution of the data. Overall survival (OS) and recurrence-free survival (RFS) curves were generated by the Kaplan–Meier method, and group comparisons were performed using the log-rank test. To explore prognostic factors for OS and RFS, univariable Cox proportional hazards models were fitted first; covariates with a P-value < 0.10 were then included in multivariable Cox models to identify variables independently associated with outcome. Results are reported as hazard ratios (HRs) with 95% confidence intervals (CIs). Statistical significance was defined as a two-sided P-value < 0.05. To reduce selection bias and improve comparability between the ILND and non-ILND groups, propensity score matching (PSM) was performed using the “MatchIt” package in R (version 4.4.3; R Foundation for Statistical Computing). Propensity scores were estimated using a multivariable logistic regression model that included sex, age, smoking history, symptoms at diagnosis, family history of malignant tumors, tumor differentiation, histological type, tumor laterality, visceral pleural invasion, bronchial invasion, number of lymph node stations dissected, total number of dissected lymph nodes, and receipt of adjuvant chemotherapy. Patients were matched 1:1 using nearest-neighbor matching without replacement with a caliper of 0.3 on the logit of the propensity score. Covariate balance before and after matching was evaluated using standardized mean differences and visual inspection of propensity score distributions. All statistical analyses were performed using R software (version 4.4.3). The “MatchIt” package was used for PSM, and the “survival” and “survminer” packages were used to perform survival analyses and generate Kaplan-Meier curves and forest plots. Results Patient Characteristics in the Original Cohort The clinicopathological characteristics of the study population are summarized in Table 1 . In the original cohort of 597 patients with pathological stage IB NSCLC, 262 (43.9%) did not undergo ILND and 335 (56.1%) did. Overall, 425 patients (71.2%) were male and 192 (32.2%) were older than 65 years. A history of smoking was present in 348 patients (58.3%), and 353 (59.1%) were symptomatic at diagnosis. Most patients (501, 83.9%) reported no family history of malignant tumors. Adenocarcinoma was the predominant histological subtype (397, 66.5%), followed by squamous cell carcinoma (200, 33.5%). Visceral pleural invasion and bronchial invasion were observed in 358 (60.0%) and 152 (25.5%) patients, respectively. Lymph node dissection involved ≥ 6 stations in 169 patients (28.3%), and ≥ 12 lymph nodes were removed in 328 patients (54.9%). Postoperative chemotherapy was administered to 96 patients (16.1%), and disease progression occurred in 250 patients (41.9%). Table 1 Comparison of clinicopathological characteristics between the original and propensity score–matched cohorts according to interlobar lymph node dissection Variables Original data set Matched data set Total Interlobar lymph node dissection P value Total Interlobar lymph node dissection P value N = 597 No (N = 262) Yes (N = 335) N = 458 No (N = 229) Yes (N = 229) Sex 0.364 0.917 Female 172(28.8%) 70(11.7%) 102(17.1%) 128(27.9%) 63(13.8%) 65(14.2%) Male 425(71.2%) 192(32.2%) 233(39.0%) 330(72.1%) 166(36.2%) 164(35.8%) Age 0.271 0.483 > 65 192(32.2%) 91(15.2%) 101(16.9%) 146 (31.9%) 77 (16.8%) 69 (15.1%) ≤ 65 405(67.8%) 171(28.6%) 234(39.2%) 312 (68.1%) 152 (33.2%) 160 (34.9%) Smoking 0.193 0.567 No 249(41.7%) 101(16.9%) 148(24.8%) 183(40.0%) 88(19.2%) 95(20.7%) Yes 348(58.3%) 161(27.0%) 187(31.3%) 275(60%) 141(30.8%) 134(29.3%) Symptom 1.000 0.924 No 244(40.9%) 107(17.9%) 137(22.9%) 186(40.6%) 92(20.1%) 94(20.5%) Yes 353(59.1%) 155(26.0%) 198(33.2%) 272(59.4%) 137(29.9%) 135(29.5%) Family history of malignant tumor 0.053 0.601 No 501(83.9%) 229(38.4%) 272(45.6%) 389(84.9%) 197(43.0%) 192(41.9%) Yes 96(16.1%) 33(5.5%) 63(10.6%) 69 (15.1%) 32 (7.0%) 37 (8.1%) Differentiation 0.152 1.000 Poorly/undifferentiated 237(39.7%) 113(18.9%) 124(20.8%) 186(40.6%) 93(20.3%) 93(20.3%) Moderately/well differentiated 360(60.3%) 149(25.0%) 211(35.3%) 272(59.4%) 136(29.7%) 136(29.7%) Histology 0.127 0.690 Adenocarcinoma 397(66.5%) 165(27.6%) 232(38.9%) 309(67.5%) 152(33.2%) 157(34.3%) Squamous 200(33.5%) 97(16.2%) 103(17.3%) 149(32.5%) 77(16.8%) 72(15.7%) Visceral Pleural Invasion 0.051 1.0000 No 239(40.0%) 117(19.6%) 122(20.4%) 179(39.1%) 90(19.7%) 89(19.4%) Yes 358(60.0%) 145(24.3%) 213(35.7%) 279(60.9%) 139(30.3%) 140(30.6%) Bronchial Invasion 1.000 0.666 No 445(74.54%) 195(32.7%) 250(41.9%) 343(74.9%) 169(36.9%) 174(38.0%) Yes 152(25.46%) 67(11.2%) 85(14.2%) 115(25.1%) 60(13.1%) 55(12.0%) Number of lymph node stations dissected <0.001 0.112 <6 428(71.7%) 220(36.9%) 208(34.8%) 359(78.4%) 187(40.8%) 172(37.6%) ≥ 6 169(28.3%) 42(7.0%) 127(21.3%) 99(21.6%) 42(9.2%) 57(12.4%) Number of lymph nodes dissected <0.001 0.304 <12 269(45.1%) 151(25.3%) 118(19.8%) 232(50.7%) 122(26.6%) 110(24.0%) ≥ 12 328(54.9%) 111(18.6%) 217(36.3%) 226(49.3%) 107(23.4%) 119(26.0%) Chemotherapy 0.153 1.000 No 501(83.9%) 213(35.7%) 288(48.2%) 384(83.8%) 192(41.9%) 192(41.9%) Yes 96(16.1%) 49(8.2%) 47(7.9%) 74(16.2%) 37(8.1%) 37(8.1%) Before propensity score matching (PSM), patients in the ILND group had a significantly greater number of dissected lymph node stations and a higher total number of dissected lymph nodes than those in the non- ILND group (both P < 0.05). In contrast, sex, age, smoking status, family history of malignant tumors, histological subtype, visceral pleural invasion, bronchial invasion, adjuvant chemotherapy and tumor progression did not differ significantly between patients with and without ILND (all P > 0.05). After 1:1 PSM, 458 patients (229 per group) were included in the matched cohort. As shown in Table 1 and the propensity score density plot (Fig. 1), all baseline clinicopathological characteristics were well balanced between the ILND and non- ILND groups, and no significant differences were observed in any of the covariates (all P > 0.05). Prognostic Factors for OS and RFS Before PSM Cox proportional hazards regression analyses were performed in the original cohort of 597 patients to identify prognostic factors for overall survival (OS) and recurrence-free survival (RFS). The results of the univariate analyses are presented in Table 2 . Variables with a P-value < 0.10 in univariate analysis were entered into the multivariable Cox models. Table 2 Univariate Cox regression analyses of overall survival and recurrence-free survival before propensity score matching Variables Total Overall survival Recurrence free survival N = 597 HR (95% CI) P value HR (95% CI) P value Sex 0.87 0.414 0.93 0.585 Male 425(71.2%) reference reference Female 172(28.8%) [0.63–1.22] [0.70–1.22] Age 1.68 65 192(32.2%) [1.25–2.26] [1.02–1.72] Smoking 1.28 0.099 1.07 0.594 No 249(41.7%) reference reference Yes 348(58.3%) [0.95–1.73] [0.83–1.38] Symptom 1.32 0.072 1.18 0.206 No 244(40.9%) reference reference Yes 353(59.1%) [0.97–1.78] [0.91–1.52] Family history of malignant tumor 0.62 0.027 0.75 0.106 No 501(83.9%) reference reference Yes 96(16.1%) [0.40–0.97] [0.52–1.08] Differentiation 0.87 0.341 0.90 0.406 Poorly/undifferentiated 237(39.7%) reference reference Moderately/well differentiated 360(60.3%) [0.65–1.16] [0.70–1.16] Histology 0.85 0.289 0.78 0.066 Adenocarcinoma 397(66.5%) reference reference Squamous 200(33.5%) [0.62–1.16] [0.59–1.02] Visceral Pleural Invasion 0.98 0.882 1.13 0.342 No 239(40.0%) reference reference Yes 358(60.0%) [0.73–1.31] [0.88–1.46] Bronchial Invasion 0.75 0.121 0.81 0.161 No 445(74.5%) reference reference Yes 152(25.5%) [0.52–1.09] [0.60–1.10] interlobar lymph node dissection 0.89 0.446 0.85 0.197 No 262(43.9%) reference reference Yes 335(56.1%) [0.67–1.19] [0.66–1.09] Number of lymph node stations dissected 0.72 0.055 0.86 0.282 < 6 428(71.7%) reference reference ≥ 6 169(28.3%) [0.51–1.02] [0.65–1.14] Number of lymph nodes dissected 0.65 0.004 0.75 0.025 < 12 269(45.1%) reference reference ≥ 12 328(54.9%) [0.49–0.87] [0.59–0.97] Chemotherapy 0.55 0.009 0.78 0.165 No 501(83.9%) reference reference Yes 96(16.1%) [0.34–0.89] [0.54–1.12] For OS, the multivariable analysis demonstrated that age, family history of malignant tumors and the number of dissected lymph nodes were independent prognostic factors. Older age, a positive family history of malignant tumors and a lower number of dissected lymph nodes were associated with worse OS (all P 0.05). The hazard ratios and 95% confidence intervals for the multivariable model of OS are illustrated in Fig. 2 . For RFS, age and the number of dissected lymph nodes were identified as independent prognostic factors in the multivariable model (both P 0.05). Patients of older age and those with fewer dissected lymph nodes had significantly poorer RFS. ILND was again not associated with RFS in univariate or multivariable analyses (P > 0.05). The multivariable Cox regression results for RFS are summarized in Fig. 3 . Survival Analysis Before and After PSM Kaplan–Meier survival analyses were used to compare OS and RFS between patients who did and did not undergo ILND in both the original and matched cohorts. In the entire cohort of 597 patients, Kaplan–Meier analysis showed that OS and RFS were comparable between the ILND and non-ILND groups, and none of the log-rank tests reached statistical significance (all P > 0.05). After 1:1 PSM, 458 patients (229 in each group) were included in the matched cohort, and baseline characteristics were well balanced. As illustrated in Fig. 4 , the Kaplan–Meier curves for OS and RFS nearly overlapped between the ILND and non-ILND groups, and no significant differences in either outcome were detected (all log-rank P > 0.05). Thus, even after adjustment for baseline confounders, ILND did not translate into an observable survival benefit in pathological stage IB NSCLC. Discussion Systematic lymph node dissection (SLND) has long been regarded as a cornerstone of radical surgery for lung cancer, providing accurate pathological staging and therapeutic clearance of nodal disease. However, the optimal range of lymph node removal remains controversial, particularly in NSCLC, with clinical practice varying from mediastinal lymph node sampling (MLS) to complete SLND [ 15 ]. Several investigations have reported that SLND outperforms more limited procedures—such as MLS, selective lymph node dissection (SLND) or restricted nodal sampling—by achieving higher 5-year survival and lower rates of nodal metastasis[ 16 – 19 ]. Conversely, other data suggest that SLND is not indispensable for all patients, especially those with stage IB NSCLC, in whom routine ILND (ILND) may be unnecessary. Subsequent studies have reported that, in early-stage NSCLC, lobe-specific SLND (L-SLND) achieves 5-year overall survival and disease-free survival comparable to those obtained with more selective lymphadenectomy [ 20 ]. In addition, L-SLND has been associated with fewer postoperative complications—such as pneumonia and air leaks—as well as reduced intraoperative blood loss, shorter hospitalization and a lower incidence of atrial fibrillation [ 21 – 24 ]. Taken together, these observations indicate that L-SLND may represent a preferable lymphadenectomy strategy in selected clinical scenarios. Interlobar lymph nodes are anatomically located in the intersegmental space between adjacent pulmonary lobes, surrounded by critical vascular and bronchial structures, including the pulmonary arteries, pulmonary veins and bronchi[ 25 ]. During ILND between the left upper and lower lobes, the limited anatomical space significantly hinders surgical maneuverability, increasing the risk of life-threatening hemorrhage from vascular injury. Interlobar lymph nodes are deeply embedded between interlobar bronchi, requiring additional bronchial dissection for complete removal during sublobar resection (e.g., wedge resection or segmentectomy) in early-stage lung cancer. Their deep anatomical location increases the risk of remaining lung tissue and bronchial injury[ 26 ]. Moreover, pulmonary vascular variations or abnormal bronchial patterns occur in approximately 15–20% of patients, obscuring the demarcation between interlobar lymph nodes and adjacent structures, thereby complicating intraoperative identification and safe lymph node dissection[ 27 ]. Improper handling may result in lung tissue tears, potentially causing atelectasis or infection. Additionally, damage to the recurrent laryngeal nerve could lead to hoarseness and dysphagia, ultimately prolonging postoperative recovery. Several studies have suggested that interlobar lymph nodes are commonly involved in intrapulmonary lymph node metastasis and contribute to early lung cancer dissemination alongside other intrapulmonary lymph nodes, such as segmental bronchial lymph nodes. This highlights the critical need to evaluate the necessity of early ILND. There are studies[ 28 , 29 ] that have proven the presence of occult lymph node micro metastases in regional lymph nodes among patients with N0 stage I NSCLC, with the proportion ranging from 20.4% to 44.9%. Additionally, in the study of the pattern of occult lymph node metastasis in stage I lung cancer by Young Ho Yang et al[ 10 ]., it was found that among all patients, 146 (9.7%) had metastasis to N1 lymph nodes. For these lymph nodes, the most common site was the lobar lymph nodes (n = 115, 7.6%), followed by the interlobar and hilar lymph nodes (n = 44 [2.9%] and n = 29 [1.9%], respectively). Among the patients with lymph node metastasis, among the 91 patients with upper lobe tumors, metastasis usually occurred in the upper lobe lymph nodes (79.1%, n = 72), while among the 79 patients with lower lobe tumors, metastasis usually occurred to the lower lobe lymph nodes (54.4%, n = 43). In these patients, the interlobar lymph node metastasis rate was approximately 16.6% in upper lobe metastasis and 36.7% in lower lobe metastasis. This indicates that interlobar lymph node metastasis does exist and is possible. Although it is truly rare in early-stage NSCLC, it still cannot be ignored. Regarding ILND, our results are in opposition to those of Hiroaki Kuroda et al[ 30 ]. We used propensity score matching (PSM) to minimize bias, whereas Kuroda et al. [ 31 ]applied Sasako's method (metastasis frequency × survival rate) to evaluate the therapeutic index of ILND in left upper lobe NSCLC, thereby emphasizing its significance. However, this method has limitations. It does not consider potential confounding factors such as sex, smoking status, the number of lymph nodes dissected, and the number of lymph node stations dissected. It is also subject to sample selection bias, as it only includes left upper lobe cases and does not restrict the analysis to early-stage patients. In their cohort, 36.7% of patients were pN1/N2, indicating a later stage relative to our study cohort. This led to an interlobar lymph node metastasis rate of 23.4%, far higher than in our whole-lung stage IB cohort. This dual bias, arising from anatomical location and staging, limits the generalizability of their conclusions to other lobes or early-stage patients. In contrast, our whole-lung perspective showed no statistically significant association between ILND and OS or RFS in stage IB NSCLC. Thus, early-stage NSCLC patients may not require routine ILND. This retrospective analysis involved 597 patients with stage IB NSCLC. Before PSM, the Cox proportional hazards regression model was used to evaluate prognosis. ILND was not a prognostic factor for overall survival (OS) or recurrence-free survival (RFS) in both univariate and multivariate analyses. Subsequently, patients were divided into two groups according to whether they underwent ILND. To reduce bias, they were matched at a 1:1 ratio using PSM. The Kaplan-Meier method and log-rank test were used for survival analysis. The results did not show a significant correlation between the dissection of interlobar lymph nodes and OS or RFS (P > 0.05). Age, family history of malignant tumors and the number of dissected lymph nodes were found to be predictive factors for OS. Age and the number of dissected lymph nodes were significant prognostic factors for RFS. In patients with stage IB NSCLC, ILND increases surgical complexity, prolongs operative duration, and increases the incidence of postoperative complications, offering minimal benefits in terms of overall survival (OS) and recurrence-free survival (RFS). Our analysis reveals no statistically significant association between ILND and OS or RFS in patients with stage IB NSCLC. This study has several limitations. First, it was conducted at a single institution and has an inherent retrospective design. Second, the cohort size was moderate, with 597 eligible patients, which may limit the statistical power for some subgroup analyses. Third, although multiple surgical teams were involved, potential differences in operative technique were not formally adjusted for and could have influenced perioperative and long-term outcomes. These factors may restrict the external validity of our results. Larger, prospective multicenter studies will be required to confirm and extend our observations. Conclusion In summary, ILND was not associated with improved OS or RFS in patients with pathological stage IB NSCLC. These data suggest that routine ILND may be safely omitted in carefully selected early-stage NSCLC patients undergoing adequate systematic lymph node dissection. Declarations Ethics approval and consent to participate This study was conducted in accordance with the Declaration of Helsinki. The protocol for secondary analysis of de-identified clinical data was reviewed and approved by the Ethics Committee of Sun Yat-sen University Cancer Center (Guangzhou, China; approval No.: B1999-011-01; approval date: 15 March 1999) and the Ethics Committee of Beijing Chest Hospital, Capital Medical University (Beijing, China; approval date: 15 June 2023). Because of the retrospective design and the use of anonymized data, the requirement for written informed consent was waived by the Ethics Committees. Consent for publication Not applicable. This study does not contain any identifiable individual person’s data. Funding The authors received no specific funding for this work. Author Contribution HC, DY, and CL contributed equally to this work. HC, DY, and CL contributed to study conception and design, data collection, and manuscript drafting. LZ, YH, and FW contributed to data interpretation and critical revision of the manuscript. LZ, YH, and FW served as the co-corresponding authors. All authors read and approved the final manuscript and agree to be accountable for all aspects of the work. Acknowledgements Not applicable. Data Availability The datasets used and/or analyzed during the current study are not publicly available due to institutional regulations and patient privacy protection. Data are available from the corresponding authors on reasonable request and with permission of the data-providing institution. References Miller KD, Nogueira L, Devasia T, Mariotto AB, Yabroff KR, Jemal A, et al. 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Supplementary Files Table1.docx Table2.docx EthicsApprovalSYSUCC.pdf EthicsApprovalBJCH.pdf Cite Share Download PDF Status: Posted Version 1 posted 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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1","display":"","copyAsset":false,"role":"figure","size":455035,"visible":true,"origin":"","legend":"\u003cp\u003ePropensity score distributions before and after propensity score matching between the ILND and non-ILND groups.\u003cbr\u003e\nAbbreviations: ILND, interlobar lymph node dissection; PSM, propensity score matching; NSCLC, non-small cell lung cancer.\u003c/p\u003e","description":"","filename":"Fig1PSdistribution.png","url":"https://assets-eu.researchsquare.com/files/rs-8433359/v1/218ff8b7ea2f2d1e820bdbb4.png"},{"id":101205567,"identity":"d0bd82df-7efc-4cb0-837c-3f39db7c30c5","added_by":"auto","created_at":"2026-01-27 09:49:45","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":747310,"visible":true,"origin":"","legend":"\u003cp\u003eForest plot of the multivariable Cox proportional hazards model for overall survival before propensity score matching.\u003cbr\u003e\nAbbreviations: HR, hazard ratio; CI, confidence interval; OS, overall survival; ILND, interlobar lymph node dissection; PSM, propensity score matching.\u003c/p\u003e","description":"","filename":"Fig2OSforest.png","url":"https://assets-eu.researchsquare.com/files/rs-8433359/v1/022c0ea07c6206b8ca264bf7.png"},{"id":101205669,"identity":"8acc9ddc-8ca2-4583-b93c-fac0050677f4","added_by":"auto","created_at":"2026-01-27 09:50:04","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":435818,"visible":true,"origin":"","legend":"\u003cp\u003eForest plot of the multivariable Cox proportional hazards model for recurrence-free survival before propensity score matching.\u003cbr\u003e\nAbbreviations: HR, hazard ratio; CI, confidence interval; RFS, recurrence-free survival; ILND, interlobar lymph node dissection; PSM, propensity score matching\u003c/p\u003e","description":"","filename":"Fig3RFSforest.png","url":"https://assets-eu.researchsquare.com/files/rs-8433359/v1/07021117e7aab138433aba8b.png"},{"id":101074101,"identity":"17a196bb-0f2c-4cc9-bccb-794531ce5843","added_by":"auto","created_at":"2026-01-25 10:19:30","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":2522950,"visible":true,"origin":"","legend":"\u003cp\u003eKaplan–Meier curves for overall survival and recurrence-free survival comparing the ILND and non-ILND groups before and after propensity score matching.\u003cbr\u003e\nAbbreviations: OS, overall survival; RFS, recurrence-free survival; ILND, interlobar lymph node dissection; PSM, propensity score matching.\u003c/p\u003e","description":"","filename":"Fig4KMcurves.png","url":"https://assets-eu.researchsquare.com/files/rs-8433359/v1/6833879e11329208b2de53ea.png"},{"id":103507044,"identity":"bac19c00-6b56-46f0-8e04-f4b3d5fdfa7d","added_by":"auto","created_at":"2026-02-26 13:40:16","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4875093,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8433359/v1/68045d24-8b90-4316-98e1-7d1ac93ce7ff.pdf"},{"id":101205072,"identity":"aa179be3-d1e2-4250-84f5-2321a8cd5d37","added_by":"auto","created_at":"2026-01-27 09:46:20","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":32857,"visible":true,"origin":"","legend":"","description":"","filename":"Table1.docx","url":"https://assets-eu.researchsquare.com/files/rs-8433359/v1/f14342f3dd54ee59e48ea8e0.docx"},{"id":101205036,"identity":"b6eb711b-30ed-425b-8111-b62a0d9f8cb3","added_by":"auto","created_at":"2026-01-27 09:45:36","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":24226,"visible":true,"origin":"","legend":"","description":"","filename":"Table2.docx","url":"https://assets-eu.researchsquare.com/files/rs-8433359/v1/1bf6abc54772652e32098a1d.docx"},{"id":101074092,"identity":"ccf6f92b-daea-423e-8566-236b8682c091","added_by":"auto","created_at":"2026-01-25 10:19:30","extension":"pdf","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":249387,"visible":true,"origin":"","legend":"","description":"","filename":"EthicsApprovalSYSUCC.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8433359/v1/cb63533eb5070b5a9cef6c8a.pdf"},{"id":101205414,"identity":"9fd425e0-59e7-4c4a-a99e-7027f47cd2e4","added_by":"auto","created_at":"2026-01-27 09:49:20","extension":"pdf","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":334223,"visible":true,"origin":"","legend":"","description":"","filename":"EthicsApprovalBJCH.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8433359/v1/07111947c3f37d345600a2b9.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Assessment of the necessity of interlobar lymph node dissection in pathological stage IB non-small cell lung cancer: a propensity score-matched study","fulltext":[{"header":"Background","content":"\u003cp\u003eLung cancer is the leading cause of cancer-related deaths worldwide, with non-small cell lung cancer (NSCLC) accounting for the predominant proportion[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Since Cahan first reported 48 cases of radical lobectomy in 1960, this surgical procedure has gradually become the standard of surgical treatment for lung cancer[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Lymph node (LN) metastasis is a critical predictor of prognosis in NSCLC[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Currently, systematic lymph node dissection (SLND) is recognized as a key tool to provide more accurate tumor staging and improve patient survival by removing potential micrometastases[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. With the development of surgical techniques, including robot-assisted thoracoscopic surgery (RATS) and video-assisted thoracoscopic surgery (VATS), the visualization of lymph node regions has been significantly enhanced[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The difficulty of systematic lymph node dissection has been significantly reduced. However, excessive lymph node dissection may elevate the risk of postoperative complications, such as hemorrhage, chylothorax, cardiovascular disease and nerve injury[\u003cspan additionalcitationids=\"CR8 CR9\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Furthermore, in the case of lung surgery, studies have shown that longer surgical duration is linked to higher mortality risk[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Systematic mediastinal lymphadenectomy (SMLD) inevitably prolongs the duration of surgery, which in turn increases the risk of such complications[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. In summary, how to ensure accurate tumor staging while selecting the most appropriate lymph node dissection scope and minimizing surgical trauma remains a central challenge in clinical practice.\u003c/p\u003e \u003cp\u003eSystematic lymph node dissection (SLND) has long been a cornerstone in the surgical management of NSCLC, supported by a body of robust clinical evidence that underscores its role in improving 5-year survival rates, particularly in early-stage disease. However, recent studies have questioned the necessity of SLND, particularly in patients with clinically lymph node-negative (cN0) disease. These studies indicate that lobe-specific systematic nodal dissection (L-SND) may yield comparable oncological outcomes to conventional SLND. Interlobar lymph nodes are located in the lung parenchyma between lobar and segmental bronchi and occupy concealed anatomical positions adjacent to pulmonary lobes. These lymph nodes are surrounded by critical structures, including pulmonary arteries, veins and bronchi. The narrow surgical field in this region significantly increases procedural complexity. SLND should include stations 2R, 4R, 7, 8 and 9 for right-sided cancers and stations 4L, 5, 6, 7, 8 and 9 for left-sided lung cancers[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. However, the necessity of routine dissection of these lymph nodes remains controversial[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. By now, there are no studies on the necessity of dissection of interlobar lymph nodes in patients with stage IB NSCLC. In this study, we aimed to evaluate the impact of ILND on survival outcomes in patients with stage IB NSCLC.\u003c/p\u003e \u003cp\u003eGiven the aforementioned controversies, this study aims to evaluate the survival benefits of ILND in patients with stage IB NSCLC and to provide evidence-based guidance for optimizing surgical strategies in early-stage NSCLC.\u003c/p\u003e"},{"header":"Methods","content":"\u003cp\u003ePatients and Study Design\u003c/p\u003e \u003cp\u003eBetween January 1999 and December 2009, clinical data were retrospectively collected from patients with NSCLC who underwent radical lung cancer surgery at Sun Yat-Sen University Cancer Center. The inclusion criteria were as follows: i) pathologically confirmed NSCLC; ii) pathological stage IB disease; and iii) no history of neoadjuvant therapy prior to surgery. All cases were re-staged according to the 8th edition of the IASLC/AJCC TNM classification based on pathological tumor size and lymph node status. All pathological diagnoses were independently confirmed by two experienced pathologists.\u003c/p\u003e \u003cp\u003eThe exclusion criteria were: i) incomplete or missing lymph node information; ii) presence of severe cardiovascular disease, autoimmune disease or active preoperative infection; and iii) lack of complete follow-up data. After applying these criteria, a total of 597 patients with pathological stage IB NSCLC were included in the present study.\u003c/p\u003e \u003cp\u003eFollow-up\u003c/p\u003e \u003cp\u003eAfter surgery, patients were monitored according to a structured schedule: every 3 months for the first 2 years, every 6 months between years 3 and 5, and once per year thereafter. At each visit, clinical examination, routine laboratory testing, serum tumor marker assessment, chest computed tomography and abdominal ultrasonography were performed. Brain magnetic resonance imaging was arranged annually, or earlier if neurological symptoms or other clinical suspicion arose. Overall survival (OS) was calculated from the date of resection to death from any cause or last contact. Recurrence-free survival (RFS) was measured from the date of surgery to the earliest of locoregional or distant relapse, or death from any cause; patients without an event were censored at their last recorded follow-up. The follow-up period was closed in January 2013.\u003c/p\u003e \u003cp\u003eSurgical procedures and postoperative management\u003c/p\u003e \u003cp\u003eAll patients underwent comprehensive preoperative assessment to exclude surgical contraindications. Treatment strategies were determined by a multidisciplinary team, and anatomical pulmonary resection was recommended for patients deemed suitable for surgery. Lobectomy or more extensive anatomical resection was performed in all cases.\u003c/p\u003e \u003cp\u003eSystematic lymph node dissection (SLND) was carried out in accordance with contemporary guideline-based practice. For right-sided tumors, lymphadenectomy generally included stations 2R, 4R, 7, 8 and 9, whereas for left-sided tumors, stations 4L, 5, 6, 7, 8 and 9 were routinely dissected. ILND was defined as the removal of station 11 lymph nodes located in the interlobar region between adjacent pulmonary lobes. Whether ILND was performed was determined by the operating surgeon, based on intraoperative findings and anatomical considerations.\u003c/p\u003e \u003cp\u003ePostoperative adjuvant chemotherapy was administered according to prevailing clinical practice guidelines and individual patient risk profiles, particularly in those with high-risk pathological features.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eCategorical data were described as counts with corresponding percentages and were compared between the ILND and non-ILND groups using the χ\u0026sup2; test or Fisher\u0026rsquo;s exact test when appropriate. Continuous variables were presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation or as median with interquartile range, and group differences were evaluated with the student\u0026rsquo;s t-test or Mann\u0026ndash;Whitney U test according to the distribution of the data.\u003c/p\u003e \u003cp\u003eOverall survival (OS) and recurrence-free survival (RFS) curves were generated by the Kaplan\u0026ndash;Meier method, and group comparisons were performed using the log-rank test. To explore prognostic factors for OS and RFS, univariable Cox proportional hazards models were fitted first; covariates with a P-value\u0026thinsp;\u0026lt;\u0026thinsp;0.10 were then included in multivariable Cox models to identify variables independently associated with outcome. Results are reported as hazard ratios (HRs) with 95% confidence intervals (CIs). Statistical significance was defined as a two-sided P-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003cp\u003eTo reduce selection bias and improve comparability between the ILND and non-ILND groups, propensity score matching (PSM) was performed using the \u0026ldquo;MatchIt\u0026rdquo; package in R (version 4.4.3; R Foundation for Statistical Computing). Propensity scores were estimated using a multivariable logistic regression model that included sex, age, smoking history, symptoms at diagnosis, family history of malignant tumors, tumor differentiation, histological type, tumor laterality, visceral pleural invasion, bronchial invasion, number of lymph node stations dissected, total number of dissected lymph nodes, and receipt of adjuvant chemotherapy. Patients were matched 1:1 using nearest-neighbor matching without replacement with a caliper of 0.3 on the logit of the propensity score. Covariate balance before and after matching was evaluated using standardized mean differences and visual inspection of propensity score distributions.\u003c/p\u003e \u003cp\u003eAll statistical analyses were performed using R software (version 4.4.3). The \u0026ldquo;MatchIt\u0026rdquo; package was used for PSM, and the \u0026ldquo;survival\u0026rdquo; and \u0026ldquo;survminer\u0026rdquo; packages were used to perform survival analyses and generate Kaplan-Meier curves and forest plots.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003ePatient Characteristics in the Original Cohort\u003c/p\u003e \u003cp\u003eThe clinicopathological characteristics of the study population are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. In the original cohort of 597 patients with pathological stage IB NSCLC, 262 (43.9%) did not undergo ILND and 335 (56.1%) did. Overall, 425 patients (71.2%) were male and 192 (32.2%) were older than 65 years. A history of smoking was present in 348 patients (58.3%), and 353 (59.1%) were symptomatic at diagnosis. Most patients (501, 83.9%) reported no family history of malignant tumors. Adenocarcinoma was the predominant histological subtype (397, 66.5%), followed by squamous cell carcinoma (200, 33.5%). Visceral pleural invasion and bronchial invasion were observed in 358 (60.0%) and 152 (25.5%) patients, respectively. Lymph node dissection involved\u0026thinsp;\u0026ge;\u0026thinsp;6 stations in 169 patients (28.3%), and \u0026ge;\u0026thinsp;12 lymph nodes were removed in 328 patients (54.9%). Postoperative chemotherapy was administered to 96 patients (16.1%), and disease progression occurred in 250 patients (41.9%).\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\u003eComparison of clinicopathological characteristics between the original and propensity score\u0026ndash;matched cohorts according to interlobar lymph node dissection\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"9\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" 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 \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003ctbody\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e \u003cp\u003eOriginal data set\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c9\" namest=\"c6\"\u003e \u003cp\u003eMatched data set\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eInterlobar lymph node dissection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c8\" namest=\"c7\"\u003e \u003cp\u003eInterlobar lymph node dissection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u0026thinsp;=\u0026thinsp;597\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo (N\u0026thinsp;=\u0026thinsp;262)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYes (N\u0026thinsp;=\u0026thinsp;335)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eN\u0026thinsp;=\u0026thinsp;458\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNo (N\u0026thinsp;=\u0026thinsp;229)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003eYes (N\u0026thinsp;=\u0026thinsp;229)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.364\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.917\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e172(28.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e70(11.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e102(17.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e128(27.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e63(13.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e65(14.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e425(71.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e192(32.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e233(39.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e330(72.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e166(36.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e164(35.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.271\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.483\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e192(32.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e91(15.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e101(16.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e146 (31.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e77 (16.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e69 (15.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e405(67.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e171(28.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e234(39.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e312 (68.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e152 (33.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e160 (34.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSmoking\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.193\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.567\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e249(41.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e101(16.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e148(24.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e183(40.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e88(19.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e95(20.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e348(58.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e161(27.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e187(31.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e275(60%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e141(30.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e134(29.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSymptom\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.924\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e244(40.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e107(17.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e137(22.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e186(40.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e92(20.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e94(20.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e353(59.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e155(26.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e198(33.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e272(59.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e137(29.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e135(29.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFamily history of malignant tumor\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.053\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.601\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e501(83.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e229(38.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e272(45.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e389(84.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e197(43.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e192(41.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e96(16.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33(5.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63(10.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e69 (15.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e32 (7.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e37 (8.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDifferentiation\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.152\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePoorly/undifferentiated\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e237(39.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e113(18.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e124(20.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e186(40.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e93(20.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e93(20.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModerately/well differentiated\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e360(60.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e149(25.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e211(35.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e272(59.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e136(29.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e136(29.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistology\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.127\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.690\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e397(66.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e165(27.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e232(38.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e309(67.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e152(33.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e157(34.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSquamous\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e200(33.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e97(16.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e103(17.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e149(32.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e77(16.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e72(15.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVisceral Pleural Invasion\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.051\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1.0000\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e239(40.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e117(19.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e122(20.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e179(39.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e90(19.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e89(19.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e358(60.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e145(24.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e213(35.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e279(60.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e139(30.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e140(30.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBronchial Invasion\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.666\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e445(74.54%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e195(32.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e250(41.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e343(74.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e169(36.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e174(38.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e152(25.46%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e67(11.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e85(14.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e115(25.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e60(13.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e55(12.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of lymph node stations dissected\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.112\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e428(71.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e220(36.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e208(34.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e359(78.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e187(40.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e172(37.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e169(28.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42(7.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e127(21.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e99(21.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e42(9.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e57(12.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of lymph nodes dissected\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.304\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e269(45.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e151(25.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e118(19.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e232(50.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e122(26.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e110(24.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e328(54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e111(18.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e217(36.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e226(49.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e107(23.4%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e119(26.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChemotherapy\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\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.153\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e1.000\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e501(83.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e213(35.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e288(48.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e384(83.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e192(41.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e192(41.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e96(16.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e49(8.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e47(7.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e74(16.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e37(8.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e \u003cp\u003e37(8.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eBefore propensity score matching (PSM), patients in the ILND group had a significantly greater number of dissected lymph node stations and a higher total number of dissected lymph nodes than those in the non- ILND group (both P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In contrast, sex, age, smoking status, family history of malignant tumors, histological subtype, visceral pleural invasion, bronchial invasion, adjuvant chemotherapy and tumor progression did not differ significantly between patients with and without ILND (all P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eAfter 1:1 PSM, 458 patients (229 per group) were included in the matched cohort. As shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and the propensity score density plot (Fig.\u0026nbsp;1), all baseline clinicopathological characteristics were well balanced between the ILND and non- ILND groups, and no significant differences were observed in any of the covariates (all P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003ePrognostic Factors for OS and RFS Before PSM\u003c/p\u003e \u003cp\u003eCox proportional hazards regression analyses were performed in the original cohort of 597 patients to identify prognostic factors for overall survival (OS) and recurrence-free survival (RFS). The results of the univariate analyses are presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Variables with a P-value\u0026thinsp;\u0026lt;\u0026thinsp;0.10 in univariate analysis were entered into the multivariable Cox models.\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\u003eUnivariate Cox regression analyses of overall survival and recurrence-free survival before propensity score matching\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" 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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariables\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eOverall survival\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eRecurrence free survival\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u0026thinsp;=\u0026thinsp;597\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eHR (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eHR (95% CI)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.414\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.585\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e425(71.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e172(28.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.63\u0026ndash;1.22]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.70\u0026ndash;1.22]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.035\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e405(67.8%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e192(32.2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[1.25\u0026ndash;2.26]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[1.02\u0026ndash;1.72]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSmoking\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.099\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.594\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e249(41.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e348(58.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.95\u0026ndash;1.73]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.83\u0026ndash;1.38]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSymptom\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.32\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.072\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.206\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e244(40.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e353(59.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.97\u0026ndash;1.78]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.91\u0026ndash;1.52]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFamily history of malignant tumor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.027\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.106\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e501(83.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e96(16.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.40\u0026ndash;0.97]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.52\u0026ndash;1.08]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDifferentiation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.341\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.406\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePoorly/undifferentiated\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e237(39.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eModerately/well differentiated\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e360(60.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.65\u0026ndash;1.16]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.70\u0026ndash;1.16]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistology\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.289\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.066\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e397(66.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSquamous\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e200(33.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.62\u0026ndash;1.16]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.59\u0026ndash;1.02]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVisceral Pleural Invasion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.882\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.342\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e239(40.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e358(60.0%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.73\u0026ndash;1.31]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.88\u0026ndash;1.46]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBronchial Invasion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.121\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.161\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e445(74.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e152(25.5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.52\u0026ndash;1.09]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.60\u0026ndash;1.10]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003einterlobar lymph node dissection\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.446\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.197\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e262(43.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e335(56.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.67\u0026ndash;1.19]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.66\u0026ndash;1.09]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of lymph node stations dissected\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.055\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.282\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e428(71.7%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e169(28.3%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.51\u0026ndash;1.02]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.65\u0026ndash;1.14]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of lymph nodes dissected\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.025\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e269(45.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e328(54.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.49\u0026ndash;0.87]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.59\u0026ndash;0.97]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChemotherapy\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.165\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=\"left\" colname=\"c2\"\u003e \u003cp\u003e501(83.9%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003ereference\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e96(16.1%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e[0.34\u0026ndash;0.89]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e[0.54\u0026ndash;1.12]\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eFor OS, the multivariable analysis demonstrated that age, family history of malignant tumors and the number of dissected lymph nodes were independent prognostic factors. Older age, a positive family history of malignant tumors and a lower number of dissected lymph nodes were associated with worse OS (all P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). ILND was not significantly associated with OS in either univariate or multivariable analysis (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The hazard ratios and 95% confidence intervals for the multivariable model of OS are illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFor RFS, age and the number of dissected lymph nodes were identified as independent prognostic factors in the multivariable model (both P\u0026thinsp;\u0026lt;\u0026thinsp;0.05), whereas histological subtype did not retain statistical significance (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Patients of older age and those with fewer dissected lymph nodes had significantly poorer RFS. ILND was again not associated with RFS in univariate or multivariable analyses (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The multivariable Cox regression results for RFS are summarized in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSurvival Analysis Before and After PSM\u003c/p\u003e \u003cp\u003eKaplan\u0026ndash;Meier survival analyses were used to compare OS and RFS between patients who did and did not undergo ILND in both the original and matched cohorts. In the entire cohort of 597 patients, Kaplan\u0026ndash;Meier analysis showed that OS and RFS were comparable between the ILND and non-ILND groups, and none of the log-rank tests reached statistical significance (all P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003eAfter 1:1 PSM, 458 patients (229 in each group) were included in the matched cohort, and baseline characteristics were well balanced. As illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the Kaplan\u0026ndash;Meier curves for OS and RFS nearly overlapped between the ILND and non-ILND groups, and no significant differences in either outcome were detected (all log-rank P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Thus, even after adjustment for baseline confounders, ILND did not translate into an observable survival benefit in pathological stage IB NSCLC.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eSystematic lymph node dissection (SLND) has long been regarded as a cornerstone of radical surgery for lung cancer, providing accurate pathological staging and therapeutic clearance of nodal disease. However, the optimal range of lymph node removal remains controversial, particularly in NSCLC, with clinical practice varying from mediastinal lymph node sampling (MLS) to complete SLND [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Several investigations have reported that SLND outperforms more limited procedures\u0026mdash;such as MLS, selective lymph node dissection (SLND) or restricted nodal sampling\u0026mdash;by achieving higher 5-year survival and lower rates of nodal metastasis[\u003cspan additionalcitationids=\"CR17 CR18\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Conversely, other data suggest that SLND is not indispensable for all patients, especially those with stage IB NSCLC, in whom routine ILND (ILND) may be unnecessary. Subsequent studies have reported that, in early-stage NSCLC, lobe-specific SLND (L-SLND) achieves 5-year overall survival and disease-free survival comparable to those obtained with more selective lymphadenectomy [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. In addition, L-SLND has been associated with fewer postoperative complications\u0026mdash;such as pneumonia and air leaks\u0026mdash;as well as reduced intraoperative blood loss, shorter hospitalization and a lower incidence of atrial fibrillation [\u003cspan additionalcitationids=\"CR22 CR23\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Taken together, these observations indicate that L-SLND may represent a preferable lymphadenectomy strategy in selected clinical scenarios.\u003c/p\u003e \u003cp\u003eInterlobar lymph nodes are anatomically located in the intersegmental space between adjacent pulmonary lobes, surrounded by critical vascular and bronchial structures, including the pulmonary arteries, pulmonary veins and bronchi[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. During ILND between the left upper and lower lobes, the limited anatomical space significantly hinders surgical maneuverability, increasing the risk of life-threatening hemorrhage from vascular injury. Interlobar lymph nodes are deeply embedded between interlobar bronchi, requiring additional bronchial dissection for complete removal during sublobar resection (e.g., wedge resection or segmentectomy) in early-stage lung cancer. Their deep anatomical location increases the risk of remaining lung tissue and bronchial injury[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Moreover, pulmonary vascular variations or abnormal bronchial patterns occur in approximately 15\u0026ndash;20% of patients, obscuring the demarcation between interlobar lymph nodes and adjacent structures, thereby complicating intraoperative identification and safe lymph node dissection[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Improper handling may result in lung tissue tears, potentially causing atelectasis or infection. Additionally, damage to the recurrent laryngeal nerve could lead to hoarseness and dysphagia, ultimately prolonging postoperative recovery. Several studies have suggested that interlobar lymph nodes are commonly involved in intrapulmonary lymph node metastasis and contribute to early lung cancer dissemination alongside other intrapulmonary lymph nodes, such as segmental bronchial lymph nodes. This highlights the critical need to evaluate the necessity of early ILND.\u003c/p\u003e \u003cp\u003eThere are studies[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] that have proven the presence of occult lymph node micro metastases in regional lymph nodes among patients with N0 stage I NSCLC, with the proportion ranging from 20.4% to 44.9%. Additionally, in the study of the pattern of occult lymph node metastasis in stage I lung cancer by Young Ho Yang et al[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]., it was found that among all patients, 146 (9.7%) had metastasis to N1 lymph nodes. For these lymph nodes, the most common site was the lobar lymph nodes (n\u0026thinsp;=\u0026thinsp;115, 7.6%), followed by the interlobar and hilar lymph nodes (n\u0026thinsp;=\u0026thinsp;44 [2.9%] and n\u0026thinsp;=\u0026thinsp;29 [1.9%], respectively). Among the patients with lymph node metastasis, among the 91 patients with upper lobe tumors, metastasis usually occurred in the upper lobe lymph nodes (79.1%, n\u0026thinsp;=\u0026thinsp;72), while among the 79 patients with lower lobe tumors, metastasis usually occurred to the lower lobe lymph nodes (54.4%, n\u0026thinsp;=\u0026thinsp;43). In these patients, the interlobar lymph node metastasis rate was approximately 16.6% in upper lobe metastasis and 36.7% in lower lobe metastasis. This indicates that interlobar lymph node metastasis does exist and is possible. Although it is truly rare in early-stage NSCLC, it still cannot be ignored.\u003c/p\u003e \u003cp\u003eRegarding ILND, our results are in opposition to those of Hiroaki Kuroda et al[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. We used propensity score matching (PSM) to minimize bias, whereas Kuroda et al. [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]applied Sasako's method (metastasis frequency \u0026times; survival rate) to evaluate the therapeutic index of ILND in left upper lobe NSCLC, thereby emphasizing its significance. However, this method has limitations. It does not consider potential confounding factors such as sex, smoking status, the number of lymph nodes dissected, and the number of lymph node stations dissected. It is also subject to sample selection bias, as it only includes left upper lobe cases and does not restrict the analysis to early-stage patients. In their cohort, 36.7% of patients were pN1/N2, indicating a later stage relative to our study cohort. This led to an interlobar lymph node metastasis rate of 23.4%, far higher than in our whole-lung stage IB cohort. This dual bias, arising from anatomical location and staging, limits the generalizability of their conclusions to other lobes or early-stage patients. In contrast, our whole-lung perspective showed no statistically significant association between ILND and OS or RFS in stage IB NSCLC. Thus, early-stage NSCLC patients may not require routine ILND.\u003c/p\u003e \u003cp\u003eThis retrospective analysis involved 597 patients with stage IB NSCLC. Before PSM, the Cox proportional hazards regression model was used to evaluate prognosis. ILND was not a prognostic factor for overall survival (OS) or recurrence-free survival (RFS) in both univariate and multivariate analyses. Subsequently, patients were divided into two groups according to whether they underwent ILND. To reduce bias, they were matched at a 1:1 ratio using PSM. The Kaplan-Meier method and log-rank test were used for survival analysis. The results did not show a significant correlation between the dissection of interlobar lymph nodes and OS or RFS (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Age, family history of malignant tumors and the number of dissected lymph nodes were found to be predictive factors for OS. Age and the number of dissected lymph nodes were significant prognostic factors for RFS.\u003c/p\u003e \u003cp\u003eIn patients with stage IB NSCLC, ILND increases surgical complexity, prolongs operative duration, and increases the incidence of postoperative complications, offering minimal benefits in terms of overall survival (OS) and recurrence-free survival (RFS). Our analysis reveals no statistically significant association between ILND and OS or RFS in patients with stage IB NSCLC.\u003c/p\u003e \u003cp\u003eThis study has several limitations. First, it was conducted at a single institution and has an inherent retrospective design. Second, the cohort size was moderate, with 597 eligible patients, which may limit the statistical power for some subgroup analyses. Third, although multiple surgical teams were involved, potential differences in operative technique were not formally adjusted for and could have influenced perioperative and long-term outcomes. These factors may restrict the external validity of our results. Larger, prospective multicenter studies will be required to confirm and extend our observations.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn summary, ILND was not associated with improved OS or RFS in patients with pathological stage IB NSCLC. These data suggest that routine ILND may be safely omitted in carefully selected early-stage NSCLC patients undergoing adequate systematic lymph node dissection.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003eThis study was conducted in accordance with the Declaration of Helsinki. The protocol for secondary analysis of de-identified clinical data was reviewed and approved by the Ethics Committee of Sun Yat-sen University Cancer Center (Guangzhou, China; approval No.: B1999-011-01; approval date: 15 March 1999) and the Ethics Committee of Beijing Chest Hospital, Capital Medical University (Beijing, China; approval date: 15 June 2023). Because of the retrospective design and the use of anonymized data, the requirement for written informed consent was waived by the Ethics Committees.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eNot applicable. This study does not contain any identifiable individual person\u0026rsquo;s data.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThe authors received no specific funding for this work.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eHC, DY, and CL contributed equally to this work. HC, DY, and CL contributed to study conception and design, data collection, and manuscript drafting. LZ, YH, and FW contributed to data interpretation and critical revision of the manuscript. LZ, YH, and FW served as the co-corresponding authors. All authors read and approved the final manuscript and agree to be accountable for all aspects of the work.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analyzed during the current study are not publicly available due to institutional regulations and patient privacy protection. Data are available from the corresponding authors on reasonable request and with permission of the data-providing institution.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMiller KD, Nogueira L, Devasia T, Mariotto AB, Yabroff KR, Jemal A, et al. Cancer treatment and survivorship statistics, 2022. 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PLoS ONE. 2015;10:e0134674. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0134674\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0134674\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Non-small cell lung cancer (NSCLC), Propensity score matching (PSM), Interlobar lymph nodes, Overall survival (OS), Recurrence-free survival (RFS)","lastPublishedDoi":"10.21203/rs.3.rs-8433359/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8433359/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eBackground\u003c/b\u003e\u003c/p\u003e \u003cp\u003eLung cancer is the leading cause of cancer-related deaths worldwide, with non-small cell lung cancer (NSCLC) being the most common type. Systematic lymph node dissection (SLND) is a standard procedure for NSCLC, but the necessity of routine interlobar lymph node dissection (ILND) in early-stage disease, particularly in stage IB NSCLC, remains debated. While ILND can be technically performed, its benefit in improving overall survival (OS) or recurrence-free survival (RFS) is unclear. The need for routine ILND remains controversial, with limited studies addressing its role in early-stage disease. This study aimed to assess whether ILND contributes to better survival outcomes in stage IB NSCLC.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods\u003c/b\u003e\u003c/p\u003e \u003cp\u003eWe retrospectively analyzed 597 IB-stage NSCLC patients who underwent radical surgery for lung cancer at Sun Yat-Sen University Cancer Center from 1999 to 2009. We used the Cox proportional hazards regression model to analyze prognostic factors. After propensity-score matching (PSM), 458 patients were selected. We applied the Kaplan-Meier method and log-rank test to compare OS and RFS.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eAmong 597 patients included in the study, 262 did not have ILND, while 335 did. According to whether the interlobar lymph nodes were dissected, 597 patients were divided into two groups. Significant differences were found between the two groups in laterality, number of dissected lymph node stations, and number of dissected lymph nodes (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Univariate and multivariate Cox analyses by the Cox proportional hazards model showed that age, family history of malignant tumors, and number of dissected lymph nodes were prognostic factors for OS (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). For RFS, age and number of dissected lymph nodes were significant (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). ILND was not associated with OS or RFS. After PSM, survival analysis using the Kaplan-Meier method and log-rank test showed no statistical association between ILND and OS or RFS (P\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e \u003cp\u003eIn stage IB NSCLC patients, ILND is not significantly associated with OS or RFS. Routine ILND is not necessary for early-stage NSCLC.\u003c/p\u003e","manuscriptTitle":"Assessment of the necessity of interlobar lymph node dissection in pathological stage IB non-small cell lung cancer: a propensity score-matched study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-25 10:19:25","doi":"10.21203/rs.3.rs-8433359/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"63af06a4-0dfb-44ee-8ff7-71654e1e1028","owner":[],"postedDate":"January 25th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-02-24T21:24:24+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-25 10:19:25","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8433359","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8433359","identity":"rs-8433359","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}