Comparison Of Prognostic Value Between Gastric Cancer And Esophageal Adenocarcinoma Staging System In Evaluation Of The Patients With Locally Advanced Siewert Type ? Adenocarcinoma Of Esophagogastric Junction

Objective:The classification system selection of Siewert type II AEG is still controversial.The aim of the study is to investigate the UICC/AJCC 8th gastric and esophageal classification system which was more rational for Siewert type ? AEG in Chinese.Methods:Firstly,to collect patients who were diagnosed as gastroesophageal junction tumors after surgery in Shanxi Provincial Cancer Hospital from November 2012 to September2013 and those patients dissected more than 16 lymph nodes,within the definition criteria of adenocarcinoma of the gastroesophageal junction,margin negative,no preoperative radio-chemotherapy,retaining the complete clinicopathological and follow-up data,Siewert type II AEG were enrolled.Secondly,according to the UICC/AJCC 8th edition gastric and esophageal adenocarcinoma TNM classification system,these patients were reclassified and stage distribution and prognosis of the two classification systems were compared.Univariate analysis was performed using the Kaplan-Meier method and multivariate analysis using the Cox proportional hazard model.The homogeneity and discriminative power of the two staging systems were compared by Likelihood Ratio chi-square and Linear Trend chi-square.-2 Loglikelihood and C-index were used to evaluate the value of the two staging systems predicting prognosis.Results:According to the inclusion criteria,70 cases of Siewert type II AEG were collected,including 1 case of T1 stage,2 cases of T2 stage,and 67 cases of T3-T4 stage.Finally,67cases of T3-T4 stage were enrolled in the study.Among the enrolled cases,60 were male and 7 were female,with an age range of 40 to 83 years(median age 61 years)and a median follow-up of 44 months.T-stage changes occurred in 30 cases:27 cases of T4a decreased to T3 and 3 cases of T4b downgraded to T4a from gastric cancer classification system to esophageal adenocarcinoma classification system.pTNM staging changes occurred in 63 patients,mainly the pTNM staging upgrade from gastric cancer classification system to esophageal adenocarcinoma classification system.The stage distribution when using gastric cancer classification system were IIA(16.4%),IIB(14.9%),IIIA(31.3%),IIIB(34.3%),IIIC(3.0%),and 5-year cumulative survival rates of IIA,IIB,IIIA,IIIB were 81.8%,70.0%,39.1%,and 36.6%,respectively(?~2=8.221,P=0.042);The stage distribution of esophageal adenocarcinoma classification system were IIB(22.4%),IIIB(40.3%),and IVA(37.3%)and 5-year cumulative survival rates were 80.0%,43.7%,and 40.0%,respectively(?~2=7.671,P=0.022).The Likelihood Ratio chi-square value and Linear Trend chi-square value of the gastric cancer classification system were all larger than the esophageal adenocarcinoma classification system(7.855vs.6.692,6.491 vs.5.351),and the-2Log likelihood estimation value of the gastric cancer classification system was smaller than the esophageal adenocarcinoma classification system(241.324.Vs.242.045),the C index of the gastric cancer classification system is larger than the esophageal adenocarcinoma classification system(0.7289 vs.0.7215).Univariate survival analysis showed that age,tumor maximum diameter,N,pTNM,adenocarcinoma differentiation type,postoperative recurrence or metastasis were all associated with 5-year survival rate(P<0.05).Multivariate survival analysis showed that age(?70),adenocarcinoma differentiation type(Mucinous adenocarcinoma or signet-ring cell carcinoma),postoperative recurrence or metastasis,gastric cancer pTNM,and esophageal adenocarcinoma pTNM were all independent prognostic factors(P<0.05).Conclusion:UICC/AJCC 8th gastric cancer pTNM staging system is superior to esophageal adenocarcinoma pTNM staging system in predicting the prognosis of Chinese locally advanced Siewert type II AEG,gastric cancer classification system is more suitable for Siewert type ? AEG.