淋巴结转移率对Ⅲ期胃癌术后辅助放疗疗效的评估作用

Effect of metastatic lymph node ratio on the prognosis of adjuvant radiotherapy for stage-Ⅲgastric cancer patients

目的探讨淋巴结转移率(MLR)对淋巴结清扫不超15枚的Ⅲ期胃癌患者(不含食管胃结合部癌)接受术后辅助放疗疗效的评估作用。方法严格按照纳入与排除标准,从美国SEER癌症数据库中纳入2010—2016年确诊的淋巴结清扫不超15枚的Ⅲ期非食管胃结合部胃癌患者590例,其中,接受胃癌手术联合辅助化疗的患者291例(手术+化疗组),接受胃癌手术联合辅助放化疗的患者299例(手术+放化疗组),对两组患者采用1∶1倾向得分匹配(PSM),回顾性分析MLR对淋巴结清扫不超15枚的Ⅲ期胃癌患者预后影响,并评估不同MLR患者选择术后辅助放疗的意义。结果根据受试者工作特征曲线(ROC)的分析结果,将0.5定为MLR的截点值。在纳入研究的两组Ⅲ期胃癌患者中,手术+放化疗组中位生存期为23个月,1、3、5年的总生存(OS)率分别为77.1%、33.2%和22.8%。手术+化疗组中位生存期为21个月,1、3、5年的OS率分别为72.2%、33.6%和23.1%,但两组患者的OS差异无统计学意义(P>0.05)。亚组分析发现,MLR≤0.5患者中手术+放化疗组与手术+化疗组的OS差异无统计学意义(P>0.05),而MLR>0.5患者中手术+放化疗组的OS明显优于手术+化疗组(χ2=8.542,P<0.05)。PSM前多因素Cox回归分析显示,种族、T、N分期、MLR和辅助放疗是影响淋巴结清扫不超15枚的Ⅲ期胃癌患者OS的重要因素(Wald=8.544、7.547、10.925、18.047、10.715,P<0.05)。两组Ⅲ期胃癌患者经PSM后分析发现,手术+放化疗组和手术+化疗组的OS差异无统计学意义(P>0.05),其中MLR≤0.5患者中手术+放化疗组与手术+化疗组的OS差异无统计学意义(P>0.05),MLR>0.5患者中手术+放化疗组的OS明显优于手术+化疗组(χ2=6.944,P<0.05)。PSM后多因素Cox回归分析显示,种族、T、N分期、MLR和辅助放疗是影响淋巴结清扫不超15枚的Ⅲ期胃癌患者OS的重要因素(Wald=7.154、8.023、7.744、17.016、4.149,P<0.05)。两组Ⅲ期胃癌患者PSM前后的预后分析结果相符。结论MLR是淋巴结清扫不超15枚的Ⅲ期胃癌术后患者预后的重要影响因素。MLR≤0.5患者的OS未见从术后辅助放疗中获益,而MLR>0.5患者则建议接受术后辅助放疗以期改善预后。

Objective To explore the effect of metastatic lymph node ratio(MLR)on the prognosis of adjuvant radiotherapy for stage-Ⅲgastric cancer patients with no more than 15 lymph nodes dissection.Methods According to the inclusion and exclusion criteria,a total of 590 patients diagnosed with stage-Ⅲgastric cancer(excluding adenocarcinoma of esophagogastric junction)were included in this study from the SEER database between 2010 and 2016.No more than 15 lymph nodes were examined in all patients.Among them,291 patients received surgery combined with adjuvant chemotherapy(surgery+chemotherapy group),and 299 patients received surgery combined with adjuvant radiochemotherapy(surgery+radiochemotherapy group).These two groups were treated with 1∶1 propensity score matching(PSM).We retrospectively analyzed the effect of MLR on prognosis of stage-Ⅲgastric cancer patients with no more than 15 lymph nodes dissection,and evaluated the significance of postoperative adjuvant radiotherapy among patients with different MLR.Results According to the analysis result of area under curve(ROC),0.5 was defined as the best cut-off point of MLR.In the two groups of patients with stage-Ⅲgastric cancer included in the study,the median survival time was 23 months in the surgery+radiochemotherapy group,and the 1-,3-,and 5-year overall survival(OS)ratio were 77.1%,33.2%and 22.8%,respectively.The median survival time was 21 months in the surgery+chemotherapy group,and the 1-,3-,and 5-year OS ratio were 72.2%,33.6%and 23.1%,respectively.There was no statistically significant difference between the two groups in OS.The result of subgroup analysis showed that there was no statistically significant difference in OS between the surgery+radiochemotherapy group and the surgery+chemotherapy group among patients with MLR≤0.5,while OS of the surgery+radiochemotherapy group was significantly better than the surgery+chemotherapy group among patients with MLR>0.5(χ2=8.542,P<0.05).Multivariate Cox regression analysis showed that race,T stage,N stage,MLR and adjuvant radiotherapy were the important factors affecting OS of stage-Ⅲgastric cancer patients with no more than 15 lymph nodes dissection(Wald=8.544,7.547,10.925,18.047,10.715,P<0.05).After PSM,there was no statistically significant difference in OS between the two groups.The result of subgroup analysis showed that there was no statistically significant difference in OS between the surgery+radiochemotherapy group and the surgery+chemotherapy group among patients with MLR≤0.5,while OS of the surgery+radiochemotherapy group was significantly better than the surgery+chemotherapy group among patients with MLR>0.5(χ2=6.944,P<0.05).Multivariate Cox regression analysis showed that race,T stage,N stage,MLR and adjuvant radiotherapy were the important factors affecting OS of stage-Ⅲgastric cancer patients with no more than 15 lymph nodes dissection(Wald=7.154,8.023,7.744,17.016,4.149,P<0.05).The result of prognosis analysis of two groups before and after PSM were consistent.Conclusions MLR is an important prognostic factor for stage-Ⅲgastric cancer patients with no more than 15 lymph nodes dissection.The OS of patients with MLR≤0.5 can′t benefit from postoperative adjuvant radiotherapy,while patients with MLR>0.5 should be advised to receive postoperative adjuvant radiotherapy to improve the prognosis.