Turning left or right? A comparative analysis in adenocarcinomas of the esophagogastric junction according to the seventh AJCC TNM classification for cancers of the esophagus and stomach: experience in a Chinese single institution

The seventh AJCC TNM classification defines rules for classifying adenocarcinomas of esophagogastric junction (AEG II and III) as a part of esophageal cancer. But there are still many controversies over the classification system. The study aims to evaluate and compare whether AEG should be classified as cancers of esophagus or stomach. A single-center cohort of patients with AEG or proximal third gastric adenocarcinoma underwent surgical resection with curative intent in Shanghai from November 2004 to July 2011. We compared the clinicopathologic features between AEG (n=291) and proximal third gastric adenocarcinoma (n=176) and analyzed overall survival probabilities of AEG using the latest seventh AJCC TNM classification for cancers. Patients with AEG not only show more advanced diseases, but also have a significantly worse 5-year survival rate than those with proximal third gastric adenocarcinoma (P=0.027). In 291 patients with AEG, the gastric T classification is monotone but indistinct except for pT2 versus pT3 (P=0.001) and pT4a versus pT4b (P=0.012). The esophageal T classification is neither monotone nor distinct. For the N classification, both schemes are monotone and distinct. The gastric scheme is indistinctive for stages IA versus IB (P=0.428), for IIA versus IIB (P=0.376), for IIB versus IIIA (P=0.086), for IIIA versus IIIB (P=0.087), and for IIIC versus IV (P=0.928). The esophageal scheme is indistinct only except for IIIB versus IIIC (P=0.002). The gastric scheme includes one heterogeneous stage group (stage IIIC, P<0.001), whereas all stage groups are homogeneous in the esophageal scheme. Although AEG shows different clinicopathological features and surgical outcomes of patients, the current seventh AJCC TNM classification which stages the AEG in the esophageal scheme does not demonstrate the advantages in the assessment of the patient prognosis. We propose a revised staging system to clarify the AEG with esophageal invasion.