Evaluation Of Lymph Nodes Ratio In Predicting Prognosis And Selecting Patients Suitable For Postoperative Adjuvant Chemotherapy In Esophageal Cancer

Objective: To investigate the value of lymph node ratio in predicting prognosis and selecting patients suitable for postoperative adjuvant chemotherapy in esophageal squamous cell carcinoma.Method:1.The clinical and pathological data of patients with thoracic esophageal squamous cell carcinoma who underwent radical resection from 2005 to 2012 were collected.2.Lymph nodes ratio(LNR)was defined as the ratio of the number of metastatic lymph nodes(pN)to the number of lymph nodes resected.Establish the cut-off points of LNR.Lymph node(N)staging was performed based on the pN and LNR stage strategies respectively.3.Evaluate the prognostic value of LNR for esophageal cancer.The survival differences between each subgroups patients with the same N stage were compared;Univariate and multivariate analysis were used to identify the prognostic variables affecting esophageal cancer;The survival difference between each subgroups patients in the same N stage were compared when classifying by another N stage strategies.The area under the ROC curve(ROC)assesses the predictive accuracy of the LNR and pN staging strategies to assess prognosis.4.The effect of postoperative chemotherapy on survival in patients with esophageal cancer was analyzed by subgroup analysis based on pN and LNR stages strategies,respectively.Result:1.A total of 380 patients were enrolled in this study,including 174 cases in surgery alone group and 206 cases in adjuvant chemotherapy group;including 185 cases of them with positive lymph nodes and 195 cases of them with negative lymph nodes.2.The cut-off points of LNR were finally established as 0,0~0.15,0.15~0.40,> 0.40.Correspondingly,we divided all patients into four stages as follows:LNR0 stage: LNR=0,LNR1 stage: 0<LNR?0.15,LNR2 stage: 0.15<LNR?0.40 and LNR3 stage: LNR> 0.40.3.The 5-year disease-free survival rate and overall survival rate among patients with different LNR stage were statistically different(P<0.05).In addition to patients with pN0 and pN1 stages,5-year disease-free survival rate and overall survival rate of patients with other pN stages was not statistically different(P>0.05).Multivariate analysis showed that both pN and LNR stage were independent factors affecting disease-free survival and overall survival,and the hazard ratio(HR)of LNR stage was higher than that of pN stage.In patients with the same N stage,survival time was significantly different between different LNR subgroups(P<0.05),but within the same LNR stage,except for patients with LNR2 stage,there was no statistical difference in the survival among the other pN subgroups(P>0.05).ROC curve analysis indicates that the area under the ROC curve(AUC=0.683,AUC=0.686)for the relationship between LNR stage and disease-free survival or overall survival was greater than that of the pN stage(AUC=0.662,AUC=0.666).4.There was no statistically significant difference in 5-year disease-free survival rate and overall survival rate between the surgery alone group and adjuvant chemotherapy group in the general population(P>0.05).For patients with pN1 stage,the 5-year overall survival rates for the surgery alone group and adjuvant chemotherapy group were 18.2% and 30.8% respectively,the difference was statistically significant(P=0.024).The 5-year disease-free survival rate for adjuvant chemotherapy group showed benefit trend(23.2% vs 9.1%),but difference was not statistically significant(P=0.067).For patients with pN0,pN2,and pN3 stage,the 5-year disease-free and overall survival rates in the adjuvant chemotherapy group did not show survival benefit(P>0.05).For patients with LNR1 stage,the 5-year disease-free survival rate of the surgery alone group and adjuvant chemotherapy groups was 18.1% and 32.9% respectively,the difference was statistically significant(P=0.004).The 5-year overall survival rates of the two treatment groups were 18.9% and 39.8%,respectively,and the difference was statistically significant(P=0.003).For patients with LNR2 and LNR3 stage,the 5-year disease-free and overall survival rates in the adjuvant chemotherapy group did not show survival benefit(P>0.05).Stratified analysis according to LNR stage strategies in the same pN stage showed that adjuvant chemotherapy could only improve median DFS and OS in patients with LNR1 stage both in pN1 and pN2 to pN3 patients.Conclusion: LNR is an independent prognostic factor affecting the prognosis of patients with esophageal squamous cell carcinoma,and its ability predicting prognosis was superior to pN stage.The benefit of postoperative adjuvant chemotherapy may be limited to patients with lower lymph node rate(0<LNR?0.15).