How to classify adenocarcinomas of the esophagogastric junction: as esophageal or gastric cancer?

Abstract

Background: To evaluate whether so-called cardiac adenocarcinomas (adenocarcinomas of the esophagogastric junction type II and III, ie AEG II and III) are better staged as cancers of the esophagus or as cancers of the stomach.

Methods: A single-center cohort of 1141 patients operated for AEG II and III is staged according to the seventh edition of the TNM classification for cancers of the esophagus and cancers of the stomach. Kaplan-Meier and Cox regression analyses are used to evaluate the prognostic performance of these 2 staging schemes.

Results: For so-called cardiac adenocarcinomas, the esophageal T classification is monotone. That is, it defines subgroups with continuous decreasing survival with increasing T stage. And it is distinct. That is, survival of these monotonic subgroups differs significantly. The gastric T classification is monotone but not distinct for pT2 versus pT3 (P=0.641) and for pT4a versus pT4b tumors (P=0.130). The type of infiltrated adjacent structure matters with significant differences in prognosis between the esophageal subgroups T4a and T4b (P<0.001). For the N classification, both the esophageal and gastric schemes are monotone and distinct, with decreasing prognosis with increasing number of lymph node metastases. The subclassification of N3a and N3b disease according to the gastric scheme defines 2 subgroups with significant differences in prognosis (P<0.01). Both the gastric and esophageal schemes include heterogeneous stage groups (2 and 1, respectively) and are not distinctive between several stage groups (4 and 3, respectively).

Conclusions: Neither the esophageal nor the gastric scheme proves to be clearly superior over the other, and neither is perfect for AEG II and III. Our analysis includes further hints that so-called cardiac adenocarcinomas have different biological properties compared with genuine gastric and genuine esophageal cancers.