Based on pN-stage to Identify Gastric Carcinoma Patients with Overall Survival Benefit from Postoperative Radiotherapy: A Propensity Score Matching Analysis and Subgroup Analysis

Based on pN-stage to Identify Gastric Carcinoma Patients with Overall Survival Benefit from Postoperative Radiotherapy: A Propensity Score Matching Analysis and Subgroup Analysis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Based on pN-stage to Identify Gastric Carcinoma Patients with Overall Survival Benefit from Postoperative Radiotherapy: A Propensity Score Matching Analysis and Subgroup Analysis Guangmin Wan, Gang Wang, Lu Yang, Gang Xu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4727635/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: It is currently controversial whether regional lymph node status is related to the benefit of postoperative radiotherapy for gastric cancer. Methods: All surgically treated patients with more than 15 lymph nodes examined diagnosed by positive histology between January 2007–December 2019 were included from the SEER database. All the patients receiving adjuvant chemotherapy were subsequently compared by propensity score matching (PSM), with overall survival (OS) as the endpoint, adjuvant radiotherapy (ART) as the only variable. Results of subgroup analyses are presented in a forest plot. Results: There are 1882 patients included in this study, 1301(69.1%) patients in the ART group and 581(30.9%) patients in the no-ART group. After PSM, each group included 573 patients. Overall, ART did not significantly improve 3-year overall survival (OS; 55.5% vs 51.1%, p = 0.07). However, in the subgroup of patients with pathologic lymph node metastasis (pN 3 -stage), 55-70 years old, tumor size > 89mm and T 3 -stage benefited from postoperative radiotherapy (p < 0.05). We further performed PSM and survival analysis on total patients with different pathological lymph node stages to validate the role of ART. We statistically observed survival benefits in pN + (positive pathologic lymph node) and pN 3 groups, but no similar effects were observed in pN 1 and pN 2 groups. For pN 0 groups, although the results showed no statistical significance, we believe that ART should not be performed. Conclusion: ART significantly improved prognosis in the patients with pN 3 -stage. More researches are needed to further validate the role of ART for gastric cancer. Biological sciences/Cancer Health sciences/Oncology gastric cancer ART PSM subgroup analysis pN-stage Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction Gastric cancers (GC) have been known as one of the most common causes of cancer mortality both in the world( 1 ). Recent years, the surgery remains the cornerstone of curative treatment for non-metastatic gastric cancer. A cochrane systematic review and meta-analysis advocated D2 lymphadenectomy is the recommended surgical approach for individuals with resectable gastric cancer( 2 ). Unfortunately, despite a curative gastrectomy, 40–65% of individuals with locally advanced gastric cancer will develop locoregional recurrence. Recurrence following total resection of stomach cancer generally occurs within two years( 3 ). Adjuvant and neoadjuvant treatments have been implemented in the management of GC. Pre-treatment seeks to reduce tumors and eradicate circulating malignant cells, whereas perioperative chemotherapy is the accepted standard of care. Some study also suggested survival benefit when radiotherapy (RT) was added to preoperative chemotherapy in patients with locally advanced adenocarcinoma of the oesophagogastric junction( 4 ). For locally gastric cancer with positive regional lymph nodes, postoperative or preoperative chemotherapy (CT) is regraded as a primary recommendation, but ART only be considered as an individual recommendation in patients with an R1 resection, although radiotherapy helps to control micro-metastasis( 5 – 7 ). ESMO and Korean clinical guideline notes that adjuvant chemoradiotherapy (CRT) can be considered for patients who have not received preoperative CT and have not undergone an appropriate D2 lymphadenectomy, ART has no benefit and should not be given for patients undergoing peri- or post-operative CT and surgery with clear margins( 6 , 8 ). At present, some studies have explored the role of ART in GC patients. Since 2001, there has been ongoing research into the role of adjuvant chemoradiotherapy (CRT) in the management of gastric cancer. A prospective study conducted at that time revealed that the combination of local-regional radiotherapy and fluorinated pyrimidine led to significant improvements in overall and relapse-free survival for gastric cancer patients( 9 ). Subsequent studies, such as INT-0116 and the Netherlands Cancer Registry Overall study, further supported the benefits of adjuvant CRT in terms of overall survival and relapse-free survival. These findings were reaffirmed in a follow-up study with 10-year observation period( 10 , 11 ). Interestingly, CRITICS series trial showed that the adjuvant CT group had a significantly better 5-year overall survival, better event-free survival and lower peritoneal metastases than the adjuvant CRT group in per-protocol (PP) analysis for patients who completed the neoadjuvant therapy, but the Intention-to-treat (ITT) analysis did not show survival benefit between the two treatment arms ( 12 , 13 ). Therefore, the role of adjuvant radiotherapy in the treatment of patients with resected GC has not been well established. Furthermore, various research studies have demonstrated that GC patients who undergo postoperative treatment may not fully comply, regardless of whether they received preoperative treatment( 9 , 12 , 14 ). This lack of compliance can be attributed to factors such as patient refusal, disease progression, toxicity from preoperative treatment, poor health condition, and mortality.( 13 ). In cases where neoadjuvant treatment was not administered, it should be noted that which subsets of patients who maybe benefit from the addition of ART to adjuvant chemotherapy. Evidently, there is a need for corresponding risk stratification to obtain a better prediction of prognosis and to identify the best patient candidate for postoperative RT. At present, certain studies have shown that the lymph node ratio and lymph node status are the most important prognostic factors in patients with resected GC, and it has been widely debated whether pathological lymph node status plays an important role in guiding the application of postoperative radiotherapy( 15 , 16 ). This cohort study describes the pattern of ART provision for gastric cancer patients from the SEER database during the 2007–2019 based on pN-stage. We aimed to analyze the impact of with or not ART on overall survival and identified patient subsets associated with the administration of ART in actual clinical practice. Material and methods Study population This retrospective study utilized 2007–2019 tumor registries, which derived from SEER database. It collects tumor clinicopathological information from population-based cancer registries covering about 30.0% of the U.S. population. The SEER Research Data (2000–2020), which collected clinicopathological, therapeutic, and follow-up data from 17 cancer registries, was submitted in November 2022. SEER* Statistics 8.4.3 software was used to extract key information from patients with GC. We determined eligible patients based on the following inclusion criteria: ( 1 ) all patients were diagnosed by histopathological examination; ( 2 ) with only one primary tumor; ( 3 ) receiving adjuvant chemotherapy; ( 4 ) survival time ≥ 3 months; ( 5 ) regional lymph nodes examined ≥ 15. The exclusion criteria are as follows: ( 1 ) metastatic disease at the time of diagnosis; ( 2 ) receiving neoadjuvant therapy including radiotherapy and chemotherapy; ( 3 ) patients with unclear clinicopathological characteristics, such as regional positive lymph nodes, race, tumor size et al. Figure 1 depicts a flow chart for patient screening. Covariates The following variables were included in the analysis: age at diagnosis, sex, marital status at diagnosis, year of diagnosis, race, primary tumor site, grade, tumor size, T-stage, pN-stage, regional nodes positive, regional nodes examined, surgery of primary tumors, sequence of surgery and chemotherapy, sequence of surgery and radiation, vital status and survival months. The race was classified as white, black, other (American Indian/AK Native, Asian/ Pacific Islander). Widowed, separated, divorced, or single (a domestic partner, or never married) of the patients were classified as unmarried. Histological grade was divided into grade I ~ II and III ~ IV. Cardiac and fundus of the stomach were classified as upper 1/3; the body of the stomach is classified as middle 1/3; gastric antrum and pylorus were divided into lower 1/3; lesser curvature of stomach, not otherwise stated (NOS), greater curvature of stomach NOS were classified as curvature, overlapping lesion of the stomach and stomach NOS classified as others. T-stage was divided into T 1 , T 2 , T 3 , T 4 . The pN-stage of all patients is derived from surgical evaluation and the number of positive nodes based on the eighth version of AJCC tumor staging, including pN 0 , pN 1 , pN 2 , and pN 3 . The surgery was divided into partial or subtotal, near-total or total, others (with or not resection of other organs). Beam radiation recode was divided into ART and No- ART. The X-tile software was used to determine the appropriate cutoff values for the levels of age at diagnosis and tumor size( 17 ). Specifically, age (years) was divided into 70, tumor size (mm) was divided into 89. Statistical analysis The study endpoints were OS defined as the time from the patient’s initial diagnosis to death from any cause. The information of 1882 patients were retrieved from the SEER database and analyzed and plotted using R version 4.3.1( https://www.r-project.org/ ). Using the “MatchIt” package, Propensity score matching (PSM) aimed to address imbalances in vital baseline characteristics between the two groups( 18 ). According to with or not adjuvant radiotherapy, a 1:1 nearest neighbor PSM analysis with a caliper of 0.1 was carried out to optimize the matching process and achieve a balanced comparison between the two groups. 3-years OS and median overall survival were calculated and graphed by Kaplan–Meier methods and compared by log-rank tests after performing PSM. A forest plot was created for all the time-to-event variables, and hazard ratio (HR), 95% confidence interval (CI), and p value were calculated. p < 0.05 was the threshold of significance. The present study used previously collected anonymized and de-identified data from the SEER database, which does not require Institutional Review Board approval. Result Population analysis A total of 93212 cases of the first malignant primary GC were indexed between 2000 and 2021 from the SEER database,17 Registries, Nov 2023 Sub (2000–2021). There are 8352 patients receiving postoperative beam radiation therapy, which accounts for 8.96%. The annual postmastectomy radiotherapy incidence from 2000 to 2021 are shown in Fig. 2 . The line graph shows that the number of gastric cancer patients receiving postoperative radiotherapy is gradually decreasing from 574 in 2000 to 130 in 2021. The SEER program has identified and abstracted data on the sequence of systemic therapy and surgery of the GC since 2007. Therefore, we extracted clinical data from 2007 to 2019. Overall, 1882 patients participated in this retrospective analysis, of which 1301 were treated with ART while the remaining 581 were not. The demographic and clinical characteristics of these patients are shown in Table 1 . Baseline characteristics, including race, sex, marital status, grade, histological type and surgical method (p > 0.05), were no significant differences between the two groups before PSM, as presented in Table 1 . Notably, patients who underwent ART were significantly younger compared to the no-ART group. Patients more than 70 years old in no-ART group account for 24.6%. Compared to the no-ART group, ART group shows more superficial local infiltration, more affected lymph nodes, smaller tumor size (p 0.05). Table 1 Demographic and clinical characteristics. Characteristics Before PSM After PSM ART(n = 1301) Number(%) Non-ART(n = 581) Number(%) P value ART(n = 573) Number(%) Non-ART(n = 573) Number(%) P value Race 0.169 0.778 White 732 (56.3) 353 (60.8) 343 (59.9) 346 (60.4) Black 177 (13.6) 75 (12.9) 83 (14.5) 75 (13.1) Others1 392 (30.1) 153 (26.3) 147 (25.7) 152 (26.5) Age(years) 0.023 0.858 70 250 (19.2) 143 (24.6) 133 (23.2) 141 (24.6) Sex 0.216 1.000 Male 811 (62.3) 344 (59.2) 342 (59.7) 341 (59.5) Female 490 (37.7) 237 (40.8) 231 (40.3) 232 (40.5) Marital status 0.058 1.000 Married 929 (71.4) 389 (67.0) 387 (67.5) 386 (67.4) Unmarried 372 (28.6) 192 (33.0) 186 (32.5) 187 (32.6) Site 0.009 0.877 1/3 U 244 (18.8) 117 (20.1) 126 (22.0) 116 (20.2) 1/3 M 162 (12.5) 68 (11.7) 74 (12.9) 67 (11.7) 1/3 L 461 (35.4) 174 (29.9) 166 (29.0) 174 (30.4) curvature 260 (20.0) 110 (18.9) 107 (18.7) 109 (19.0) Others2 174 (13.4) 112 (19.3) 100 (17.5) 107 (18.7) Size(mm) 0.005 0.964 89 143 (11.0) 95 (16.4) 87 (15.2) 89 (15.5) Grade 0.940 0.832 I ~ II 283 (21.8) 128 (22.0) 132 (23.0) 128 (22.3) III ~ IV 1018 (78.2) 453 (78.0) 441 (77.0) 445 (77.7) Histological type 0.924 0.913 AC 488 (37.5) 220 (37.9) 225 (39.3) 218 (38.0) SRC 327 (25.1) 151 (26.0) 142 (24.8) 149 (26.0) ITAC 210 (16.1) 87 (15.0) 92 (16.1) 87 (15.2) Others3 276 (21.2) 123 (21.2) 114 (19.9) 119 (20.8) T 0.013 0.841 T1 103 (7.9) 45 (7.7) 49 (8.6) 45 (7.9) T2 645 (49.6) 270 (46.5) 268 (46.8) 270 (47.1) T3 424 (32.6) 178 (30.6) 183 (31.9) 176 (30.7) T4 129 (9.9) 88 (15.1) 73 (12.7) 82 (14.3) pN 0.018 0.600 pN 0 168 (12.9) 96 (16.5) 101 (17.6) 93 (16.2) pN 1 254 (19.5) 114 (19.6) 118 (20.6) 114 (19.9) pN 2 322 (24.8) 110 (18.9) 93 (16.2) 110 (19.2) pN 3 557 (42.8) 261 (44.9) 261 (45.5) 256 (44.7) Surgery 0.257 0.849 Partial or subtotal 668 (51.3) 277 (47.7) 284 (49.6) 275 (48.0) Near-total or total 228 (17.5) 117 (20.1) 113 (19.7) 114 (19.9) Others4 405 (31.1) 187 (32.2) 176 (30.7) 184 (32.1) PSM propensity score matching, AC adenocarcinoma, SRC signet ring carcinoma, ITAC intestinal-type adenocarcinoma; Others1 including Asian or Pacific Islander et al; 1/3U Cardiac and fundus of the stomach; 1/3M the body of the stomach; 1/3L gastric antrum and pylorus; curvature lesser or greater curvature of stomach; Others2 overlapping lesion of the stomach and stomach NOS; Others3 including mucinous adenocarcinoma et al; Others4 including with or not removal of a portion of other organs et al. Survival analysis for total patients Before PSM in Fig. 3 A, the 3- year OS rates were 57.0% for the ART group and 50.9% for the no-ART group (p = 0.0023). As of the follow-up period, 764 cases in the radiotherapy group have reported positive events while 357 cases in no-ART group. Besides, median OS for the ART group is 49 months (95%CI: 44–60 months), the other group’s median OS is 39 months (95%CI: 33–49 months). It shows more better prognosis than the no-ART group before PSM. After PSM in Fig. 3 B, a total of 573 pairs of patients were included in our study. ART didn’t be demonstrated significant improvements in 3-year OS (55.5% vs 51.1%, p = 0.07), the number of patients experienced positive events in ART group (n = 347) were approximately equal to the no-ART group (n = 351). Median OS for the ART group is 48 months (95%CI: 39– 60 months), the other group’s median OS is 40 months (95%CI: 33–51 months). In a word, our study didn’t indicate the ART show the positive role to improve the overall survival of total gastric cancer patients after PSM, but there was a tendency for higher OS in the ART group. Subgroup analysis after PSM To further explore the potential role of ART in gastric cancer, we conducted subgroup analysis on all patients after PSM in Fig. 4 . Patients were stratified based on age, sex, marital status, race, primary tumor site, grade, tumor size, T-stage, pN-stage, surgery of primary tumors. We explored the prognostic impact of ART on various clinical subgroups and found that ART demonstrated a significant enhanced prognostic impact in pN 3 -stage, 55–70 years old, tumor size > 89mm, and T 3 -stage subgroups (p < 0.05). But, as to pN 0 subgroups, ART seemed to result adverse effects on prognosis (p < 0.05). Survival analysis based on pN-stage We further investigated the effect of ART on patients for each pN-stage group from the SEER database. Different pN-stage patients were also adjusted with 1:1 ratio propensity score matching. Before PSM in Fig. 5 , for pN 0 subgroups, no-ART result better effects on prognosis (p = 0.023). For other subgroups, ART prolonged the long-term OS time for pN + , pN 2 , pN 3 -stage patients, which indicated patients with positive lymph nodes can benefit from postoperative adjuvant radiotherapy (p < 0.05). In addition, after PSM as shown in Fig. 6 , for 79 pairs of pN 0 -stage no-ART still result better effects on prognosis, although p value is more than 0.05. 109 pairs of pN 1 -stage and 101 pairs of pN 2 -stage subgroups were included in further analysis, respectively. Unluckily, we didn’t confirm that ART generate better effects on prognosis (p > 0.05). Interestingly, for 477 pairs of pN + subgroups and 247 pairs of pN 3 -stage subgroups, ART were proved to result better effects on prognosis (p < 0.05). Discussion The role of the ART have been explored for gastric carcinoma with lymph node metastasis, but the findings are controversial ( 12 , 16 ). In this study, we evaluated OS among 1882 patients diagnosed with gastric carcinoma from the SEER database, aiming to investigate the therapeutic impact of ART within the context of modern systemic treatments and provide clinical guidance regarding the necessity of ART based on lymph node status. Whether based on subgroup analysis of all individuals or specific pN-stage after PSM, we have confirmed more favorable prognosis in patients with pN 3 -stage disease. Therefore, our study supports the utilization of ART in patients with pN 3 -stage disease. The quality of surgery, particularly the extent of lymph node dissection and the number of examined lymph nodes, is crucial for accurate staging. It is widely acknowledged that examining the higher number of lymph nodes reduces the likelihood of missing positive nodes, leading to more accurate pN-stage and decreased the risk of locoregional relapse( 2 ). This factor significantly impacts patient prognosis. At present, there is controversy over the the optimal number of lymph nodes to be examined. Existing research indicates that the removing more lymph nodes does not necessarily improve prognosis ( 2 , 19 ). The assessment of surgical quality in the CRITICS trial revealed that, on average, 20 lymph nodes were examined per patient. ( 20 ). Additionally, some scholars believe that for locally advanced gastric cancer, a lymph node count of ≥ 30 is necessary to improve the accuracy of prognostic evaluation in patients after surgery( 21 , 22 ). The criteria included in our study were based on current AJCC/UICC TNM (8th edition) classification, which recommends that the minimum number of regional lymph node examinations should be no less than 15. The application of ART in resected gastric cancer has long been debated, with the concept that surgery alone may not be sufficient to inhibit locoregional recurrence. Therefore, we have reason to believe that ART maybe result beneficial effects in stomach cancer. As expected, previous retrospective and prospective studies have explored the role of ART in gastric cancer, but the results are not as satisfactory when ART is added to XP (capecitabine plus cisplatin) chemotherapy, although more than 80% of patients have completed postoperative radiotherapy in XP/XRT/XP arm, which is unprecedented in other studies( 15 ). The tendency for high OS in the ART group was demonstrated in survival analysis, which didn’t show the significant difference between the two groups in our study despite PSM was used to reduce inter-group differences. Lymph nodes metastasis is visible in various stages of gastric cancer, and is one of the important factors affecting the prognosis of gastric cancer. The ARTIST trial indicated that in the subgroup of patients with pathologic lymph node metastasis at the time of surgery, patients randomly assigned to the capecitabine-based chemoradiotherapy arm exhibited improved DFS when compared with those who got capecitabine plus cisplatin alone( 15 ). Subgroup analyses in phase III trial of ARTIST showed that the addition of radiotherapy to adjuvant chemotherapy significantly improved DFS in patients with node-positive disease and with intestinal-type GC, it also found that the addition of radiotherapy on DFS and OS differed by Lauren classification and lymph node ratio( 16 ).Then, they found that the adjusted recurrence-free survival was significantly higher in the CRT group than the CT group in patients with D2 resected pathologic lymph node metastasis gastric cancer( 23 ). Subsequently, stomach tumors 2 trial (ARTIST) compared different adjuvant strategies in patients with D2-resected, stage II or III, node-positive gastric cancer, which advocated that no difference in DFS was found between S-1 with oxaliplatin and postoperative chemoradiation with S-1 and oxaliplatin. The results indicated independently of pathologic stages, Lauren histologic classification, type of surgery, or lymph node ratio. But the above therapeutic schedules were effective in prolonging DFS, when compared to S1 monotherapy( 24 ). CRITICS trial considered that OS was no benefit of CRT for patients with node positive disease or for patients with a R1 resection( 12 ). We found more than 80% patients in CRITICS underwent the D2 lymphadenectomy. It is also possible that all patients received preoperative chemotherapy, postoperative treatment did not further increase survival. In the subsequent survival analysis, it is puzzling that ART benefits in pN + subgroups, which has been confirmed in previous studies( 16 , 25 ), which seems to be similar to our results before PSM, as shown in Fig. 3 A. Therefore, the obvious drawback of their study based on the SEER database is the significant inter-group confounding factors( 25 ), so we should be cautious about this result. Perhaps one of the most interesting findings in our report was the observation of various outcome obtained by chemoradiotherapy in different pN-stages. For lymph node negative patients, gastric cancer patients without ART had better survival prognosis. No benefits were observed from ART in pN 1 -stage group. For pN 2 -stage patients, postoperative radiotherapy can indeed improve prognosis at certain extent, although we did not observe any statistical significance in the K-M curve. A study of Korea suggested that significantly higher OS was demonstrated in the pN 3b subgroup of the CRT group( 23 ),but a retrospective study from the China reported that patients with N 3a -stage GC benefitted from adjuvant CRT compared with adjuvant CT, not pN 3b -stage subgroup( 26 ). Similarly, we also reported the superiority of ART in pN 3 -stage subsets. Therefore, we suggest that pN 3 -stage group should be taken into account to support the addition of ART based on our study findings. T stage refers to the depth of tumor infiltration in GC, and it is regularly identified as an independent risk factor impacting cancer patients prognosis. Previous investigations have also found a link between age and tumor size and GC prognosis( 27 ). The outcomes of this study indicated that 50–70 years old, > 89 mm, and T 3 -stage subgroups also exhibit certain clinical significance for OS in our study. There are some reasonable explanations for this phenomenon: The meaning of tumor size is horizontal growth along the gastric wall. But for higher T staging such as T 4 , it means that the tumor invades the visceral peritoneum or adjacent structures. During the surgical resection of primary tumors, free tumor cells may spread to the peritoneal cavity and peritoneal cancer is the most common recurrence pattern, which is more than 50%( 28 ). The difficulty of surgery will also increase due to deeper infiltration, leading to surgical failure. For elderly patients, due to various potential comorbidities, organ dysfunction, decreased immune function, and poor treatment willingness( 29 ), the effect of radiotherapy cannot be highlighted either. Therefore, in addition to lymph node status, age, tumor size and T-stage maybe provide useful direction for future research. Adjuvant chemotherapy is a standard of care in patients with D2-resected GC. The US Intergroup 0116 trial, which included patients who have not received neoadjuvant therapy, demonstrated that chemoradiotherapy after resection for gastric cancer significantly improves relapse-free and overall survival among such patients but only 10 percent of the patients underwent a D2 dissection( 9 ). This may be attributed to an inadequate surgical procedure. An observational study, including 544 patients received postoperative CRT and 446 patients received surgery without further adjuvant treatment, is survival benefit of the adjuvant chemoradiation therapy in D2-resected gastric cancer patients( 30 ). There are also significant covariate differences between groups, such as age, grade, T-stage, Lauren type and AJCC stage in this study. It is of some concern that during the study period, there seemed to be a heavy selection bias between different subsets. Besides, previous studies have shown that the surgery-alone arm fared significantly worse when compared with the adjuvant chemotherapy arm in terms of DFS and OS( 31 ). Therefore, we cannot confirm whether the survival benefits come from ART or adjuvant chemotherapy in the study of the South Korea. However, we utmost minimized inter-group differences and the only variable is whether postoperative radiotherapy is accepted or not. Therefore, it is reasonable to believe that ART can improve the prognosis for patients with pN 3 -stages. There are some limitations of in our study. Above all, our study is a retrospective study based on the SEER database, due to the survival outcomes between different countries, so research results need external clinical data to be confirmed in other country. Secondly, the SEER database lacks some critical clinical data, such as the median Maruyama index (MI), which is considered to be the most important quality indicator of the lymph node dissection during gastric cancer surgery in the CRITICS-trial, the Dutch Gastric Cancer Trial and the Intergroup 0116 trial( 2 , 9 , 12 ), the type of lymph node dissection (D1, D2 or Others), the radicality of resection type (R0 or R1), particular radiotherapy and chemotherapy regimens. Lastly, as the SEER database doesn’t contain the outcome specifically related to localized recurrence, our study found that postoperative radiotherapy can indeed improve the overall survival of pN 3 -stage patients at certain extent, but further research is needed to explore whether radiotherapy can reduce local or distant recurrence and metastasis, thereby improving the overall survival of lymph node positive patients. Conclusion We found better efficacy of ART compared with non-ART in resectable gastric cancer patients with pN 3 -stage. Although most current research findings tend to favor that all treatment, consisting of docetaxel-based chemotherapy, chemoradiotherapy, or both, be administered before surgery. However, for patients with pN 3 -stage in gastric cancer who did not receive neoadjuvant therapy due to preoperative refusal or other unpredictable reasons, ART appears to enhance their survival prognosis at some extent. This conclusion certainly requires further prospective research for verification. Declarations Data availability The raw data is retrieved from the Surveillance, Epidemiology, and End Results (SEER) Program (www.seer.cancer.gov) SEER*Stat Database and is provided within the supplementary information files. Ethics statement The present study used previously collected anonymized and de-identified data from the SEER database, which does not require Institutional Review Board approval. Acknowledgments We would like to appreciate the National Cancer Institute for open access to the Surveillance, Epidemiology, and End Results (SEER) database. Funding None. Author contributions GM W collected data and analysis; GM W and L Y wrote the manuscript; Q W review the manuscript; G X designed and supervised the study. All the authors approved the final manuscript. Conflict of interest The authors declare that all have no competing interests. References H. 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Lancet Oncol 19 , 616-628 (2018).http://dx.doi.org/10.1016/s1470-2045(18)30132-3 D. Cunningham et al. , Perioperative chemotherapy versus surgery alone for resectable gastroesophageal cancer. N Engl J Med 355 , 11-20 (2006).http://dx.doi.org/10.1056/NEJMoa055531 J. Lee et al. , Phase III trial comparing capecitabine plus cisplatin versus capecitabine plus cisplatin with concurrent capecitabine radiotherapy in completely resected gastric cancer with D2 lymph node dissection: the ARTIST trial. J Clin Oncol 30 , 268-273 (2012).http://dx.doi.org/10.1200/jco.2011.39.1953 S. H. Park et al. , Phase III Trial to Compare Adjuvant Chemotherapy With Capecitabine and Cisplatin Versus Concurrent Chemoradiotherapy in Gastric Cancer: Final Report of the Adjuvant Chemoradiotherapy in Stomach Tumors Trial, Including Survival and Subset Analyses. J Clin Oncol 33 , 3130-3136 (2015).http://dx.doi.org/10.1200/jco.2014.58.3930 R. L. Camp, M. Dolled-Filhart, D. L. Rimm, X-tile: a new bio-informatics tool for biomarker assessment and outcome-based cut-point optimization. Clin Cancer Res 10 , 7252-7259 (2004).http://dx.doi.org/10.1158/1078-0432.Ccr-04-0713 P. C. Austin, An Introduction to Propensity Score Methods for Reducing the Effects of Confounding in Observational Studies. Multivariate Behav Res 46 , 399-424 (2011).http://dx.doi.org/10.1080/00273171.2011.568786 M. Sasako et al. , D2 lymphadenectomy alone or with para-aortic nodal dissection for gastric cancer. N Engl J Med 359 , 453-462 (2008).http://dx.doi.org/10.1056/NEJMoa0707035 Y. H. M. Claassen et al. , Surgicopathological Quality Control and Protocol Adherence to Lymphadenectomy in the CRITICS Gastric Cancer Trial. Ann Surg 268 , 1008-1013 (2018).http://dx.doi.org/10.1097/sla.0000000000002444 T. Sano et al. , Proposal of a new stage grouping of gastric cancer for TNM classification: International Gastric Cancer Association staging project. Gastric Cancer 20 , 217-225 (2017).http://dx.doi.org/10.1007/s10120-016-0601-9 J. Deng et al. , Validation of clinical significance of examined lymph node count for accurate prognostic evaluation of gastric cancer for the eighth edition of the American Joint Committee on Cancer (AJCC) TNM staging system. Chin J Cancer Res 30 , 477-491 (2018).http://dx.doi.org/10.21147/j.issn.1000-9604.2018.05.01 J. I. Yu et al. , Necessity of adjuvant concurrent chemo-radiotherapy in D2-resected LN-positive gastric cancer. Radiother Oncol 129 , 306-312 (2018).http://dx.doi.org/10.1016/j.radonc.2018.07.002 S. H. Park et al. , A randomized phase III trial comparing adjuvant single-agent S1, S-1 with oxaliplatin, and postoperative chemoradiation with S-1 and oxaliplatin in patients with node-positive gastric cancer after D2 resection: the ARTIST 2 trial(☆). Ann Oncol 32 , 368-374 (2021).http://dx.doi.org/10.1016/j.annonc.2020.11.017 R. Shridhar et al. , Adjuvant radiation therapy increases overall survival in node-positive gastric cancer patients with aggressive surgical resection and lymph node dissection: a SEER database analysis. Am J Clin Oncol 35 , 216-221 (2012).http://dx.doi.org/10.1097/COC.0b013e31820dbf08 M. L. Zhou et al. , Adjuvant chemoradiotherapy versus adjuvant chemotherapy for patients with N3 gastric cancer after D2/R0 resection: a retrospective study based on propensity score analyses. Cancer Manag Res 11 , 4855-4870 (2019).http://dx.doi.org/10.2147/cmar.S195130 Q. Wang et al. , Development and validation of a nomogram to predict cancer-specific survival of elderly patients with unresected gastric cancer who received chemotherapy. Sci Rep 14 , 9008 (2024).http://dx.doi.org/10.1038/s41598-024-59516-3 G. Spolverato et al. , Rates and patterns of recurrence after curative intent resection for gastric cancer: a United States multi-institutional analysis. J Am Coll Surg 219 , 664-675 (2014).http://dx.doi.org/10.1016/j.jamcollsurg.2014.03.062 Y. Kawaguchi et al. , Is surgery the best treatment for elderly gastric cancer patients? World J Gastrointest Surg 13 , 1351-1360 (2021).http://dx.doi.org/10.4240/wjgs.v13.i11.1351 S. Kim et al. , An observational study suggesting clinical benefit for adjuvant postoperative chemoradiation in a population of over 500 cases after gastric resection with D2 nodal dissection for adenocarcinoma of the stomach. Int J Radiat Oncol Biol Phys 63 , 1279-1285 (2005).http://dx.doi.org/10.1016/j.ijrobp.2005.05.005 Y. J. Bang et al. , Adjuvant capecitabine and oxaliplatin for gastric cancer after D2 gastrectomy (CLASSIC): a phase 3 open-label, randomised controlled trial. Lancet 379 , 315-321 (2012).http://dx.doi.org/10.1016/s0140-6736(11)61873-4 Additional Declarations No competing interests reported. Supplementary Files rawdata1.xlsx rawdata2.xlsx 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. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4727635","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":336334103,"identity":"1752b4f5-9c5a-4e0a-8e58-154eb811cbdd","order_by":0,"name":"Guangmin Wan","email":"","orcid":"","institution":"The Affiliated Cancer Hospital of Zhengzhou University \u0026Henan Cancer Hospital","correspondingAuthor":false,"prefix":"","firstName":"Guangmin","middleName":"","lastName":"Wan","suffix":""},{"id":336334104,"identity":"869d177f-ecda-44b9-89e5-8bdbff1fc3dc","order_by":1,"name":"Gang Wang","email":"","orcid":"","institution":"The Affiliated Cancer Hospital of Zhengzhou University \u0026Henan Cancer Hospital","correspondingAuthor":false,"prefix":"","firstName":"Gang","middleName":"","lastName":"Wang","suffix":""},{"id":336334105,"identity":"774dad15-88f1-4769-8726-e8a3d0bccbf5","order_by":2,"name":"Lu Yang","email":"","orcid":"","institution":"The Affiliated Cancer Hospital of Zhengzhou University \u0026Henan Cancer Hospital","correspondingAuthor":false,"prefix":"","firstName":"Lu","middleName":"","lastName":"Yang","suffix":""},{"id":336334106,"identity":"795f5a98-464c-4f9f-9181-a48b487a3fef","order_by":3,"name":"Gang Xu","email":"data:image/png;base64,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","orcid":"","institution":"The Affiliated Cancer Hospital of Zhengzhou University \u0026Henan Cancer Hospital","correspondingAuthor":true,"prefix":"","firstName":"Gang","middleName":"","lastName":"Xu","suffix":""}],"badges":[],"createdAt":"2024-07-12 03:27:03","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4727635/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4727635/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":62221077,"identity":"00c4addf-5651-4660-a649-6d73488864a8","added_by":"auto","created_at":"2024-08-11 12:25:31","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":52440,"visible":true,"origin":"","legend":"\u003cp\u003eThe flowchart of including and dividing patients\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-4727635/v1/5698d4b2f72c3def95366352.png"},{"id":62221078,"identity":"47cbed8f-b998-42b3-8b46-81bbe0cdd22a","added_by":"auto","created_at":"2024-08-11 12:25:31","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":95726,"visible":true,"origin":"","legend":"\u003cp\u003eThe number of GC who applied ART between 2000 and 2021.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4727635/v1/55ca3054b0d9f5a1561d46cc.png"},{"id":62221084,"identity":"39f55fe9-d56f-40f6-8527-4ea2442b6af8","added_by":"auto","created_at":"2024-08-11 12:25:31","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":565658,"visible":true,"origin":"","legend":"\u003cp\u003eKaplan–Meier curves show overall survival (OS) for patient cohort (A) before PSM and (B) after PSM, according to ART status. RT radiotherapy; No-RT radiotherapy.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4727635/v1/9e7b2d3da706a83331999524.png"},{"id":62221085,"identity":"718a1bd5-f501-4577-9567-7f0b4bbbd7ce","added_by":"auto","created_at":"2024-08-11 12:25:32","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":744650,"visible":true,"origin":"","legend":"\u003cp\u003eForest plot of hazard ratios (HRs) and 95% CIs for overall survival after PSM. AC adenocarcinoma, SRC signet ring carcinoma, ITAC intestinal-type adenocarcinoma; Others1 including Asian or Pacific Islander et al; 1/3U Cardiac and fundus of the stomach; 1/3M the body of the stomach; 1/3L gastric antrum and pylorus; curvature lesser or greater curvature of stomach; Others2 overlapping lesion of the stomach and stomach NOS; Others3 including mucinous adenocarcinoma et al; Others4 including with or not removal of a portion of other organs et al.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-4727635/v1/a324addc2783273c32d8a645.png"},{"id":62221080,"identity":"4cd10255-59a8-4af5-91d2-fdc46b097a80","added_by":"auto","created_at":"2024-08-11 12:25:31","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":752329,"visible":true,"origin":"","legend":"\u003cp\u003eSurvival analysis based on different pN-stages (A-E) before PSM, including pN\u003csub\u003e0\u003c/sub\u003e, pN\u003csub\u003e+\u003c/sub\u003e (positive pathologic lymph node), pN\u003csub\u003e1\u003c/sub\u003e, pN\u003csub\u003e2\u003c/sub\u003e, pN\u003csub\u003e3\u003c/sub\u003e-stage, respectively. RT radiotherapy; No-RT radiotherapy.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4727635/v1/8ec290a2ebc997ea2365d879.png"},{"id":62221082,"identity":"7d66e90a-8f7b-4746-9bfd-721e873bdf9d","added_by":"auto","created_at":"2024-08-11 12:25:31","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":727306,"visible":true,"origin":"","legend":"\u003cp\u003eSurvival analysis based on different pN-stages (A-E) after PSM, including pN\u003csub\u003e0\u003c/sub\u003e, pN\u003csub\u003e+\u003c/sub\u003e (positive pathologic lymph node), pN\u003csub\u003e1\u003c/sub\u003e, pN\u003csub\u003e2\u003c/sub\u003e, pN\u003csub\u003e3\u003c/sub\u003e-stage, respectively. RT radiotherapy; No-RT radiotherapy.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-4727635/v1/3007df6cf0ffae36a4044679.png"},{"id":71226453,"identity":"c5be1f53-5057-4d10-ac77-8dc3d2b196ed","added_by":"auto","created_at":"2024-12-12 10:02:30","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3788432,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4727635/v1/79111a93-adb8-4b24-8294-b50a247b10f9.pdf"},{"id":62221796,"identity":"57bb56dd-3d82-409d-a615-436db3945d61","added_by":"auto","created_at":"2024-08-11 12:33:31","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":6374377,"visible":true,"origin":"","legend":"","description":"","filename":"rawdata1.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-4727635/v1/71df497d1b9a645d7c31ee14.xlsx"},{"id":62221083,"identity":"2e8104a0-b570-4458-9b05-a33ccb57dfef","added_by":"auto","created_at":"2024-08-11 12:25:31","extension":"xlsx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":2864892,"visible":true,"origin":"","legend":"","description":"","filename":"rawdata2.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-4727635/v1/bd76a44d45993a8f244f85ea.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Based on pN-stage to Identify Gastric Carcinoma Patients with Overall Survival Benefit from Postoperative Radiotherapy: A Propensity Score Matching Analysis and Subgroup Analysis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eGastric cancers (GC) have been known as one of the most common causes of cancer mortality both in the world(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e). Recent years, the surgery remains the cornerstone of curative treatment for non-metastatic gastric cancer. A cochrane systematic review and meta-analysis advocated D2 lymphadenectomy is the recommended surgical approach for individuals with resectable gastric cancer(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). Unfortunately, despite a curative gastrectomy, 40\u0026ndash;65% of individuals with locally advanced gastric cancer will develop locoregional recurrence. Recurrence following total resection of stomach cancer generally occurs within two years(\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e). Adjuvant and neoadjuvant treatments have been implemented in the management of GC. Pre-treatment seeks to reduce tumors and eradicate circulating malignant cells, whereas perioperative chemotherapy is the accepted standard of care. Some study also suggested survival benefit when radiotherapy (RT) was added to preoperative chemotherapy in patients with locally advanced adenocarcinoma of the oesophagogastric junction(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e). For locally gastric cancer with positive regional lymph nodes, postoperative or preoperative chemotherapy (CT) is regraded as a primary recommendation, but ART only be considered as an individual recommendation in patients with an R1 resection, although radiotherapy helps to control micro-metastasis(\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e). ESMO and Korean clinical guideline notes that adjuvant chemoradiotherapy (CRT) can be considered for patients who have not received preoperative CT and have not undergone an appropriate D2 lymphadenectomy, ART has no benefit and should not be given for patients undergoing peri- or post-operative CT and surgery with clear margins(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAt present, some studies have explored the role of ART in GC patients. Since 2001, there has been ongoing research into the role of adjuvant chemoradiotherapy (CRT) in the management of gastric cancer. A prospective study conducted at that time revealed that the combination of local-regional radiotherapy and fluorinated pyrimidine led to significant improvements in overall and relapse-free survival for gastric cancer patients(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). Subsequent studies, such as INT-0116 and the Netherlands Cancer Registry Overall study, further supported the benefits of adjuvant CRT in terms of overall survival and relapse-free survival. These findings were reaffirmed in a follow-up study with 10-year observation period(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e). Interestingly, CRITICS series trial showed that the adjuvant CT group had a significantly better 5-year overall survival, better event-free survival and lower peritoneal metastases than the adjuvant CRT group in per-protocol (PP) analysis for patients who completed the neoadjuvant therapy, but the Intention-to-treat (ITT) analysis did not show survival benefit between the two treatment arms (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). Therefore, the role of adjuvant radiotherapy in the treatment of patients with resected GC has not been well established.\u003c/p\u003e \u003cp\u003eFurthermore, various research studies have demonstrated that GC patients who undergo postoperative treatment may not fully comply, regardless of whether they received preoperative treatment(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e). This lack of compliance can be attributed to factors such as patient refusal, disease progression, toxicity from preoperative treatment, poor health condition, and mortality.(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e). In cases where neoadjuvant treatment was not administered, it should be noted that which subsets of patients who maybe benefit from the addition of ART to adjuvant chemotherapy. Evidently, there is a need for corresponding risk stratification to obtain a better prediction of prognosis and to identify the best patient candidate for postoperative RT.\u003c/p\u003e \u003cp\u003eAt present, certain studies have shown that the lymph node ratio and lymph node status are the most important prognostic factors in patients with resected GC, and it has been widely debated whether pathological lymph node status plays an important role in guiding the application of postoperative radiotherapy(\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). This cohort study describes the pattern of ART provision for gastric cancer patients from the SEER database during the 2007\u0026ndash;2019 based on pN-stage. We aimed to analyze the impact of with or not ART on overall survival and identified patient subsets associated with the administration of ART in actual clinical practice.\u003c/p\u003e"},{"header":"Material and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003eThis retrospective study utilized 2007\u0026ndash;2019 tumor registries, which derived from SEER database. It collects tumor clinicopathological information from population-based cancer registries covering about 30.0% of the U.S. population. The SEER Research Data (2000\u0026ndash;2020), which collected clinicopathological, therapeutic, and follow-up data from 17 cancer registries, was submitted in November 2022. SEER* Statistics 8.4.3 software was used to extract key information from patients with GC. We determined eligible patients based on the following inclusion criteria: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) all patients were diagnosed by histopathological examination; (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) with only one primary tumor; (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) receiving adjuvant chemotherapy; (\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e) survival time\u0026thinsp;\u0026ge;\u0026thinsp;3 months; (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e) regional lymph nodes examined\u0026thinsp;\u0026ge;\u0026thinsp;15. The exclusion criteria are as follows: (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e) metastatic disease at the time of diagnosis; (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e) receiving neoadjuvant therapy including radiotherapy and chemotherapy; (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e) patients with unclear clinicopathological characteristics, such as regional positive lymph nodes, race, tumor size et al. Figure\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e depicts a flow chart for patient screening.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eCovariates\u003c/h2\u003e \u003cp\u003eThe following variables were included in the analysis: age at diagnosis, sex, marital status at diagnosis, year of diagnosis, race, primary tumor site, grade, tumor size, T-stage, pN-stage, regional nodes positive, regional nodes examined, surgery of primary tumors, sequence of surgery and chemotherapy, sequence of surgery and radiation, vital status and survival months. The race was classified as white, black, other (American Indian/AK Native, Asian/ Pacific Islander). Widowed, separated, divorced, or single (a domestic partner, or never married) of the patients were classified as unmarried. Histological grade was divided into grade I\u0026thinsp;~\u0026thinsp;II and III\u0026thinsp;~\u0026thinsp;IV. Cardiac and fundus of the stomach were classified as upper 1/3; the body of the stomach is classified as middle 1/3; gastric antrum and pylorus were divided into lower 1/3; lesser curvature of stomach, not otherwise stated (NOS), greater curvature of stomach NOS were classified as curvature, overlapping lesion of the stomach and stomach NOS classified as others. T-stage was divided into T\u003csub\u003e1\u003c/sub\u003e, T\u003csub\u003e2\u003c/sub\u003e, T\u003csub\u003e3\u003c/sub\u003e, T\u003csub\u003e4\u003c/sub\u003e. The pN-stage of all patients is derived from surgical evaluation and the number of positive nodes based on the eighth version of AJCC tumor staging, including pN\u003csub\u003e0\u003c/sub\u003e, pN\u003csub\u003e1\u003c/sub\u003e, pN\u003csub\u003e2\u003c/sub\u003e, and pN\u003csub\u003e3\u003c/sub\u003e. The surgery was divided into partial or subtotal, near-total or total, others (with or not resection of other organs). Beam radiation recode was divided into ART and No- ART. The X-tile software was used to determine the appropriate cutoff values for the levels of age at diagnosis and tumor size(\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e). Specifically, age (years) was divided into \u0026lt;\u0026thinsp;55, 55\u0026ndash;70, \u0026gt; 70, tumor size (mm) was divided into \u0026lt;\u0026thinsp;26, 26\u0026ndash;89, \u0026gt; 89.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eThe study endpoints were OS defined as the time from the patient\u0026rsquo;s initial diagnosis to death from any cause. The information of 1882 patients were retrieved from the SEER database and analyzed and plotted using R version 4.3.1(\u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.r-project.org/\u003c/span\u003e\u003cspan address=\"https://www.r-project.org/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e). Using the \u0026ldquo;MatchIt\u0026rdquo; package, Propensity score matching (PSM) aimed to address imbalances in vital baseline characteristics between the two groups(\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e). According to with or not adjuvant radiotherapy, a 1:1 nearest neighbor PSM analysis with a caliper of 0.1 was carried out to optimize the matching process and achieve a balanced comparison between the two groups. 3-years OS and median overall survival were calculated and graphed by Kaplan\u0026ndash;Meier methods and compared by log-rank tests after performing PSM. A forest plot was created for all the time-to-event variables, and hazard ratio (HR), 95% confidence interval (CI), and p value were calculated. p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was the threshold of significance. The present study used previously collected anonymized and de-identified data from the SEER database, which does not require Institutional Review Board approval.\u003c/p\u003e \u003c/div\u003e"},{"header":"Result","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003ePopulation analysis\u003c/h2\u003e \u003cp\u003eA total of 93212 cases of the first malignant primary GC were indexed between 2000 and 2021 from the SEER database,17 Registries, Nov 2023 Sub (2000\u0026ndash;2021). There are 8352 patients receiving postoperative beam radiation therapy, which accounts for 8.96%. The annual postmastectomy radiotherapy incidence from 2000 to 2021 are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The line graph shows that the number of gastric cancer patients receiving postoperative radiotherapy is gradually decreasing from 574 in 2000 to 130 in 2021.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe SEER program has identified and abstracted data on the sequence of systemic therapy and surgery of the GC since 2007. Therefore, we extracted clinical data from 2007 to 2019. Overall, 1882 patients participated in this retrospective analysis, of which 1301 were treated with ART while the remaining 581 were not. The demographic and clinical characteristics of these patients are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Baseline characteristics, including race, sex, marital status, grade, histological type and surgical method (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), were no significant differences between the two groups before PSM, as presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Notably, patients who underwent ART were significantly younger compared to the no-ART group. Patients more than 70 years old in no-ART group account for 24.6%. Compared to the no-ART group, ART group shows more superficial local infiltration, more affected lymph nodes, smaller tumor size (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). After PSM, 1146 patients were successfully matched in a 1:1 ratio, achieving balanced clinical baseline characteristics in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\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\u003eDemographic and clinical characteristics.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" 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=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCharacteristics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eBefore PSM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eAfter PSM\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eART(n\u0026thinsp;=\u0026thinsp;1301)\u003c/p\u003e \u003cp\u003eNumber(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNon-ART(n\u0026thinsp;=\u0026thinsp;581)\u003c/p\u003e \u003cp\u003eNumber(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eART(n\u0026thinsp;=\u0026thinsp;573)\u003c/p\u003e \u003cp\u003eNumber(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNon-ART(n\u0026thinsp;=\u0026thinsp;573)\u003c/p\u003e \u003cp\u003eNumber(%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRace\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.169\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.778\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWhite\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e732 (56.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e353 (60.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e343 (59.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e346 (60.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBlack\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e177 (13.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e75 (12.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e83 (14.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e75 (13.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOthers1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e392 (30.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e153 (26.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e147 (25.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e152 (26.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge(years)\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.023\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.858\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e407 (31.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e178 (30.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e176 (30.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e173 (30.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e55\u0026ndash;70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e644 (49.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e260 (44.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e264 (46.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e259 (45.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e250 (19.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e143 (24.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e133 (23.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e141 (24.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.216\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e811 (62.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e344 (59.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e342 (59.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e341 (59.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\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=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e490 (37.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e237 (40.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e231 (40.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e232 (40.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMarital status\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.058\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e1.000\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMarried\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e929 (71.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e389 (67.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e387 (67.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e386 (67.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUnmarried\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e372 (28.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e192 (33.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e186 (32.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e187 (32.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSite\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.877\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1/3 U\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e244 (18.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e117 (20.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e126 (22.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e116 (20.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1/3 M\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e162 (12.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e68 (11.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e74 (12.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e67 (11.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1/3 L\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e461 (35.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e174 (29.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e166 (29.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e174 (30.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ecurvature\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e260 (20.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e110 (18.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e107 (18.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e109 (19.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOthers2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e174 (13.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e112 (19.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100 (17.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e107 (18.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSize(mm)\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.964\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e206 (15.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e89 (15.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e92 (16.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e89 (15.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e26\u0026ndash;89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e952 (73.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e397 (68.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e394 (68.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e395 (68.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e143 (11.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e95 (16.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e87 (15.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e89 (15.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGrade\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.940\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.832\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eI\u0026thinsp;~\u0026thinsp;II\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e283 (21.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e128 (22.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e132 (23.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e128 (22.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIII\u0026thinsp;~\u0026thinsp;IV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1018 (78.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e453 (78.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e441 (77.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e445 (77.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHistological type\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.924\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.913\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e488 (37.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e220 (37.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e225 (39.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e218 (38.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSRC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e327 (25.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e151 (26.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e142 (24.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e149 (26.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eITAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e210 (16.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e87 (15.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e92 (16.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e87 (15.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOthers3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e276 (21.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e123 (21.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e114 (19.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e119 (20.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.841\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e103 (7.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e45 (7.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e49 (8.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e45 (7.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e645 (49.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e270 (46.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e268 (46.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e270 (47.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e424 (32.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e178 (30.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e183 (31.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e176 (30.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eT4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e129 (9.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e88 (15.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e73 (12.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e82 (14.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epN\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.600\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epN\u003csub\u003e0\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e168 (12.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e96 (16.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e101 (17.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e93 (16.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epN\u003csub\u003e1\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e254 (19.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e114 (19.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e118 (20.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e114 (19.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epN\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e322 (24.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e110 (18.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e93 (16.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e110 (19.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epN\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e557 (42.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e261 (44.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e261 (45.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e256 (44.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSurgery\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=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.257\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.849\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePartial or subtotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e668 (51.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e277 (47.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e284 (49.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e275 (48.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNear-total or total\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e228 (17.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e117 (20.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e113 (19.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e114 (19.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOthers4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e405 (31.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e187 (32.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e176 (30.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e184 (32.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003ePSM propensity score matching, AC adenocarcinoma, SRC signet ring carcinoma, ITAC intestinal-type adenocarcinoma; Others1 including Asian or Pacific Islander et al; 1/3U Cardiac and fundus of the stomach; 1/3M the body of the stomach; 1/3L gastric antrum and pylorus; curvature lesser or greater curvature of stomach; Others2 overlapping lesion of the stomach and stomach NOS; Others3 including mucinous adenocarcinoma et al; Others4 including with or not removal of a portion of other organs et al.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eSurvival analysis for total patients\u003c/h2\u003e \u003cp\u003eBefore PSM in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA, the 3- year OS rates were 57.0% for the ART group and 50.9% for the no-ART group (p\u0026thinsp;=\u0026thinsp;0.0023). As of the follow-up period, 764 cases in the radiotherapy group have reported positive events while 357 cases in no-ART group. Besides, median OS for the ART group is 49 months (95%CI: 44\u0026ndash;60 months), the other group\u0026rsquo;s median OS is 39 months (95%CI: 33\u0026ndash;49 months). It shows more better prognosis than the no-ART group before PSM. After PSM in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB, a total of 573 pairs of patients were included in our study. ART didn\u0026rsquo;t be demonstrated significant improvements in 3-year OS (55.5% vs 51.1%, p\u0026thinsp;=\u0026thinsp;0.07), the number of patients experienced positive events in ART group (n\u0026thinsp;=\u0026thinsp;347) were approximately equal to the no-ART group (n\u0026thinsp;=\u0026thinsp;351). Median OS for the ART group is 48 months (95%CI: 39\u0026ndash; 60 months), the other group\u0026rsquo;s median OS is 40 months (95%CI: 33\u0026ndash;51 months). In a word, our study didn\u0026rsquo;t indicate the ART show the positive role to improve the overall survival of total gastric cancer patients after PSM, but there was a tendency for higher OS in the ART group.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eSubgroup analysis after PSM\u003c/h2\u003e \u003cp\u003eTo further explore the potential role of ART in gastric cancer, we conducted subgroup analysis on all patients after PSM in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Patients were stratified based on age, sex, marital status, race, primary tumor site, grade, tumor size, T-stage, pN-stage, surgery of primary tumors. We explored the prognostic impact of ART on various clinical subgroups and found that ART demonstrated a significant enhanced prognostic impact in pN\u003csub\u003e3\u003c/sub\u003e-stage, 55\u0026ndash;70 years old, tumor size\u0026thinsp;\u0026gt;\u0026thinsp;89mm, and T\u003csub\u003e3\u003c/sub\u003e-stage subgroups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). But, as to pN\u003csub\u003e0\u003c/sub\u003e subgroups, ART seemed to result adverse effects on prognosis (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eSurvival analysis based on pN-stage\u003c/h2\u003e \u003cp\u003eWe further investigated the effect of ART on patients for each pN-stage group from the SEER database. Different pN-stage patients were also adjusted with 1:1 ratio propensity score matching. Before PSM in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, for pN\u003csub\u003e0\u003c/sub\u003e subgroups, no-ART result better effects on prognosis (p\u0026thinsp;=\u0026thinsp;0.023). For other subgroups, ART prolonged the long-term OS time for pN\u003csub\u003e+\u003c/sub\u003e, pN\u003csub\u003e2\u003c/sub\u003e, pN\u003csub\u003e3\u003c/sub\u003e-stage patients, which indicated patients with positive lymph nodes can benefit from postoperative adjuvant radiotherapy (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In addition, after PSM as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, for 79 pairs of pN\u003csub\u003e0\u003c/sub\u003e-stage no-ART still result better effects on prognosis, although p value is more than 0.05. 109 pairs of pN\u003csub\u003e1\u003c/sub\u003e-stage and 101 pairs of pN\u003csub\u003e2\u003c/sub\u003e-stage subgroups were included in further analysis, respectively. Unluckily, we didn\u0026rsquo;t confirm that ART generate better effects on prognosis (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Interestingly, for 477 pairs of pN\u003csub\u003e+\u003c/sub\u003e subgroups and 247 pairs of pN\u003csub\u003e3\u003c/sub\u003e-stage subgroups, ART were proved to result better effects on prognosis (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe role of the ART have been explored for gastric carcinoma with lymph node metastasis, but the findings are controversial (\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e). In this study, we evaluated OS among 1882 patients diagnosed with gastric carcinoma from the SEER database, aiming to investigate the therapeutic impact of ART within the context of modern systemic treatments and provide clinical guidance regarding the necessity of ART based on lymph node status. Whether based on subgroup analysis of all individuals or specific pN-stage after PSM, we have confirmed more favorable prognosis in patients with pN\u003csub\u003e3\u003c/sub\u003e-stage disease. Therefore, our study supports the utilization of ART in patients with pN\u003csub\u003e3\u003c/sub\u003e-stage disease.\u003c/p\u003e \u003cp\u003eThe quality of surgery, particularly the extent of lymph node dissection and the number of examined lymph nodes, is crucial for accurate staging. It is widely acknowledged that examining the higher number of lymph nodes reduces the likelihood of missing positive nodes, leading to more accurate pN-stage and decreased the risk of locoregional relapse(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e). This factor significantly impacts patient prognosis. At present, there is controversy over the the optimal number of lymph nodes to be examined. Existing research indicates that the removing more lymph nodes does not necessarily improve prognosis (\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e). The assessment of surgical quality in the CRITICS trial revealed that, on average, 20 lymph nodes were examined per patient. (\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e). Additionally, some scholars believe that for locally advanced gastric cancer, a lymph node count of \u0026ge;\u0026thinsp;30 is necessary to improve the accuracy of prognostic evaluation in patients after surgery(\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e). The criteria included in our study were based on current AJCC/UICC TNM (8th edition) classification, which recommends that the minimum number of regional lymph node examinations should be no less than 15.\u003c/p\u003e \u003cp\u003eThe application of ART in resected gastric cancer has long been debated, with the concept that surgery alone may not be sufficient to inhibit locoregional recurrence. Therefore, we have reason to believe that ART maybe result beneficial effects in stomach cancer. As expected, previous retrospective and prospective studies have explored the role of ART in gastric cancer, but the results are not as satisfactory when ART is added to XP (capecitabine plus cisplatin) chemotherapy, although more than 80% of patients have completed postoperative radiotherapy in XP/XRT/XP arm, which is unprecedented in other studies(\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). The tendency for high OS in the ART group was demonstrated in survival analysis, which didn\u0026rsquo;t show the significant difference between the two groups in our study despite PSM was used to reduce inter-group differences.\u003c/p\u003e \u003cp\u003eLymph nodes metastasis is visible in various stages of gastric cancer, and is one of the important factors affecting the prognosis of gastric cancer. The ARTIST trial indicated that in the subgroup of patients with pathologic lymph node metastasis at the time of surgery, patients randomly assigned to the capecitabine-based chemoradiotherapy arm exhibited improved DFS when compared with those who got capecitabine plus cisplatin alone(\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e). Subgroup analyses in phase III trial of ARTIST showed that the addition of radiotherapy to adjuvant chemotherapy significantly improved DFS in patients with node-positive disease and with intestinal-type GC, it also found that the addition of radiotherapy on DFS and OS differed by Lauren classification and lymph node ratio(\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e).Then, they found that the adjusted recurrence-free survival was significantly higher in the CRT group than the CT group in patients with D2 resected pathologic lymph node metastasis gastric cancer(\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e). Subsequently, stomach tumors 2 trial (ARTIST) compared different adjuvant strategies in patients with D2-resected, stage II or III, node-positive gastric cancer, which advocated that no difference in DFS was found between S-1 with oxaliplatin and postoperative chemoradiation with S-1 and oxaliplatin. The results indicated independently of pathologic stages, Lauren histologic classification, type of surgery, or lymph node ratio. But the above therapeutic schedules were effective in prolonging DFS, when compared to S1 monotherapy(\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e). CRITICS trial considered that OS was no benefit of CRT for patients with node positive disease or for patients with a R1 resection(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e). We found more than 80% patients in CRITICS underwent the D2 lymphadenectomy. It is also possible that all patients received preoperative chemotherapy, postoperative treatment did not further increase survival. In the subsequent survival analysis, it is puzzling that ART benefits in pN\u003csub\u003e+\u003c/sub\u003e subgroups, which has been confirmed in previous studies(\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e), which seems to be similar to our results before PSM, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA. Therefore, the obvious drawback of their study based on the SEER database is the significant inter-group confounding factors(\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e), so we should be cautious about this result. Perhaps one of the most interesting findings in our report was the observation of various outcome obtained by chemoradiotherapy in different pN-stages. For lymph node negative patients, gastric cancer patients without ART had better survival prognosis. No benefits were observed from ART in pN\u003csub\u003e1\u003c/sub\u003e-stage group. For pN\u003csub\u003e2\u003c/sub\u003e-stage patients, postoperative radiotherapy can indeed improve prognosis at certain extent, although we did not observe any statistical significance in the K-M curve. A study of Korea suggested that significantly higher OS was demonstrated in the pN\u003csub\u003e3b\u003c/sub\u003e subgroup of the CRT group(\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e),but a retrospective study from the China reported that patients with N\u003csub\u003e3a\u003c/sub\u003e-stage GC benefitted from adjuvant CRT compared with adjuvant CT, not pN\u003csub\u003e3b\u003c/sub\u003e-stage subgroup(\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e). Similarly, we also reported the superiority of ART in pN\u003csub\u003e3\u003c/sub\u003e-stage subsets. Therefore, we suggest that pN\u003csub\u003e3\u003c/sub\u003e-stage group should be taken into account to support the addition of ART based on our study findings.\u003c/p\u003e \u003cp\u003eT stage refers to the depth of tumor infiltration in GC, and it is regularly identified as an independent risk factor impacting cancer patients prognosis. Previous investigations have also found a link between age and tumor size and GC prognosis(\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e). The outcomes of this study indicated that 50\u0026ndash;70 years old, \u0026gt; 89 mm, and T\u003csub\u003e3\u003c/sub\u003e-stage subgroups also exhibit certain clinical significance for OS in our study. There are some reasonable explanations for this phenomenon: The meaning of tumor size is horizontal growth along the gastric wall. But for higher T staging such as T\u003csub\u003e4\u003c/sub\u003e, it means that the tumor invades the visceral peritoneum or adjacent structures. During the surgical resection of primary tumors, free tumor cells may spread to the peritoneal cavity and peritoneal cancer is the most common recurrence pattern, which is more than 50%(\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e). The difficulty of surgery will also increase due to deeper infiltration, leading to surgical failure. For elderly patients, due to various potential comorbidities, organ dysfunction, decreased immune function, and poor treatment willingness(\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e), the effect of radiotherapy cannot be highlighted either. Therefore, in addition to lymph node status, age, tumor size and T-stage maybe provide useful direction for future research.\u003c/p\u003e \u003cp\u003eAdjuvant chemotherapy is a standard of care in patients with D2-resected GC. The US Intergroup 0116 trial, which included patients who have not received neoadjuvant therapy, demonstrated that chemoradiotherapy after resection for gastric cancer significantly improves relapse-free and overall survival among such patients but only 10 percent of the patients underwent a D2 dissection(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e). This may be attributed to an inadequate surgical procedure. An observational study, including 544 patients received postoperative CRT and 446 patients received surgery without further adjuvant treatment, is survival benefit of the adjuvant chemoradiation therapy in D2-resected gastric cancer patients(\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e). There are also significant covariate differences between groups, such as age, grade, T-stage, Lauren type and AJCC stage in this study. It is of some concern that during the study period, there seemed to be a heavy selection bias between different subsets. Besides, previous studies have shown that the surgery-alone arm fared significantly worse when compared with the adjuvant chemotherapy arm in terms of DFS and OS(\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e). Therefore, we cannot confirm whether the survival benefits come from ART or adjuvant chemotherapy in the study of the South Korea. However, we utmost minimized inter-group differences and the only variable is whether postoperative radiotherapy is accepted or not. Therefore, it is reasonable to believe that ART can improve the prognosis for patients with pN\u003csub\u003e3\u003c/sub\u003e-stages.\u003c/p\u003e \u003cp\u003eThere are some limitations of in our study. Above all, our study is a retrospective study based on the SEER database, due to the survival outcomes between different countries, so research results need external clinical data to be confirmed in other country. Secondly, the SEER database lacks some critical clinical data, such as the median Maruyama index (MI), which is considered to be the most important quality indicator of the lymph node dissection during gastric cancer surgery in the CRITICS-trial, the Dutch Gastric Cancer Trial and the Intergroup 0116 trial(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e), the type of lymph node dissection (D1, D2 or Others), the radicality of resection type (R0 or R1), particular radiotherapy and chemotherapy regimens. Lastly, as the SEER database doesn\u0026rsquo;t contain the outcome specifically related to localized recurrence, our study found that postoperative radiotherapy can indeed improve the overall survival of pN\u003csub\u003e3\u003c/sub\u003e-stage patients at certain extent, but further research is needed to explore whether radiotherapy can reduce local or distant recurrence and metastasis, thereby improving the overall survival of lymph node positive patients.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eWe found better efficacy of ART compared with non-ART in resectable gastric cancer patients with pN\u003csub\u003e3\u003c/sub\u003e-stage. Although most current research findings tend to favor that all treatment, consisting of docetaxel-based chemotherapy, chemoradiotherapy, or both, be administered before surgery. However, for patients with pN\u003csub\u003e3\u003c/sub\u003e-stage in gastric cancer who did not receive neoadjuvant therapy due to preoperative refusal or other unpredictable reasons, ART appears to enhance their survival prognosis at some extent. This conclusion certainly requires further prospective research for verification.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe raw data is retrieved from the Surveillance, Epidemiology, and End Results (SEER) Program (www.seer.cancer.gov) SEER*Stat Database and is provided within the supplementary information files.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;Ethics statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;The present study used previously collected anonymized and de-identified data from the SEER database, which does not require Institutional Review Board approval.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to appreciate the National Cancer Institute for open access to the Surveillance, Epidemiology, and End Results (SEER) database.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eGM W collected data and analysis; GM W and L Y wrote the manuscript; Q W review the manuscript; G X designed and supervised the study. All the authors approved the final manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that all have no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eH. Sung\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e, Global Cancer Statistics 2020: GLOBOCAN Estimates of Incidence and Mortality Worldwide for 36 Cancers in 185 Countries. \u003cem\u003eCA Cancer J Clin\u003c/em\u003e \u003cstrong\u003e71\u003c/strong\u003e, 209-249 (2021).http://dx.doi.org/10.3322/caac.21660\u003c/li\u003e\n \u003cli\u003eI. Songun, H. Putter, E. M. Kranenbarg, M. Sasako, C. 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Kim\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e, An observational study suggesting clinical benefit for adjuvant postoperative chemoradiation in a population of over 500 cases after gastric resection with D2 nodal dissection for adenocarcinoma of the stomach. \u003cem\u003eInt J Radiat Oncol Biol Phys\u003c/em\u003e \u003cstrong\u003e63\u003c/strong\u003e, 1279-1285 (2005).http://dx.doi.org/10.1016/j.ijrobp.2005.05.005\u003c/li\u003e\n \u003cli\u003eY. J. Bang\u003cem\u003e\u0026nbsp;et al.\u003c/em\u003e, Adjuvant capecitabine and oxaliplatin for gastric cancer after D2 gastrectomy (CLASSIC): a phase 3 open-label, randomised controlled trial. \u003cem\u003eLancet\u003c/em\u003e \u003cstrong\u003e379\u003c/strong\u003e, 315-321 (2012).http://dx.doi.org/10.1016/s0140-6736(11)61873-4\u003c/li\u003e\n\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":"gastric cancer, ART, PSM, subgroup analysis, pN-stage","lastPublishedDoi":"10.21203/rs.3.rs-4727635/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4727635/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eIt is currently controversial whether regional lymph node status is related to the benefit of postoperative radiotherapy for gastric cancer.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eAll surgically treated patients with more than 15 lymph nodes examined diagnosed by positive histology between January 2007–December 2019 were included from the SEER database. All the patients receiving adjuvant chemotherapy were subsequently compared by propensity score matching (PSM), with overall survival (OS) as the endpoint, adjuvant radiotherapy (ART) as the only variable. Results of subgroup analyses are presented in a forest plot.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults:\u003c/strong\u003e There are 1882 patients included in this study, 1301(69.1%) patients in the ART group and 581(30.9%) patients in the no-ART group. After PSM, each group included 573 patients. Overall, ART did not significantly improve 3-year overall survival (OS; 55.5% vs 51.1%, p = 0.07). However, in the subgroup of patients with pathologic lymph node metastasis (pN\u003csub\u003e3\u003c/sub\u003e-stage), 55-70 years old, tumor size \u0026gt; 89mm and T\u003csub\u003e3\u003c/sub\u003e-stage benefited from postoperative radiotherapy (p \u0026lt; 0.05). We further performed PSM and survival analysis on total patients with different pathological lymph node stages to validate the role of ART. We statistically observed survival benefits in pN\u003csub\u003e+\u003c/sub\u003e (positive pathologic lymph node) and pN\u003csub\u003e3\u003c/sub\u003e groups, but no similar effects were observed in pN\u003csub\u003e1\u003c/sub\u003e and pN\u003csub\u003e2\u003c/sub\u003e groups. For pN\u003csub\u003e0\u003c/sub\u003e groups, although the results showed no statistical significance, we believe that ART should not be performed.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e ART significantly improved prognosis in the patients with pN\u003csub\u003e3\u003c/sub\u003e-stage. More researches are needed to further validate the role of ART for gastric cancer.\u003c/p\u003e","manuscriptTitle":"Based on pN-stage to Identify Gastric Carcinoma Patients with Overall Survival Benefit from Postoperative Radiotherapy: A Propensity Score Matching Analysis and Subgroup Analysis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-08-11 12:25:26","doi":"10.21203/rs.3.rs-4727635/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":"beb77c7a-8f2c-4496-8d29-7f700d9d0dd8","owner":[],"postedDate":"August 11th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":35623770,"name":"Biological sciences/Cancer"},{"id":35623771,"name":"Health sciences/Oncology"}],"tags":[],"updatedAt":"2024-12-12T09:54:19+00:00","versionOfRecord":[],"versionCreatedAt":"2024-08-11 12:25:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4727635","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4727635","identity":"rs-4727635","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}