Comparison of the 8th UICC staging system for esophageal and gastric cancers in Siewert type II junctional adenocarcinomas

Abstract

Background: The aim of this study is to evaluate whether adenocarcinomas of the esophagogastric junction (AEG) are better staged as cancers of the esophagus (TNM-EC) or stomach (TNM-GC) according to the 8th edition of the UICC classification.

Methods: A single-center cohort of 246 patients operated on for AEG type II was staged according to the 8th edition of the UICC classification for esophageal and stomach cancer. Kaplan-Meier and univariate Cox regression analyses were performed to investigate the impact on survival.

Results: For AEG type II TNM-EC classified most of the patients (n = 126; 51.2%) to UICC stage IIIC and IVA while TNM-GC more evenly distributed the patients over the stages. Hazard ratios increased in between all stages in a stepwise manner except between stage IA and IIA for TNM-EC and between stage IIB and IIIA for TNM-GC. Survival curves for TNM-GC demonstrated significant differences between all four major UICC stages, while in TNM-EC no significant difference between stage I and II was found. When comparing the area under the curves of both staging systems a marginal superiority for TNM-EC was found.

Conclusion: Neither the esophageal nor the stomach staging system is flawless in predicting survival in AEG type II. A marginal superiority of the TNM-EC was found in discriminating survival rates after three and five years. However, the advantage of the TNM-GC lies in the division of the N3 category into N3a and N3b. We therefor suggest a similar division in future TNM-EC classifications to improve its prognostic value.

Keywords: AEG; Carcinoma of the esophageal gastric junction; Siewert; TNM; Tumor classification.