Background: Adenocarcinoma of esophagogastric junction (EGJ) is currently staged by the esophageal staging criteria according to the American Joint Committee on Cancer (AJCC) staging system, 7th edition. We compared the performance of 6th gastric (G6), 7th gastric (G7), and 7th esophageal (E7) staging systems. Methods: A total of 202 curatively resected adenocarcinomas of EGJ were analyzed. Patient outcomes were assessed according to G6, G7, and E7 staging. Tumor invasion to the subserosal or serosa layer was regarded as invasion to the adventitia for E7 staging. Performance was measured based on monotonicity (decreasing survival with increasing stage), distinctiveness (survival difference between different stages), and homogeneity (homogenous survival in the same stage). Results: Each staging system was monotonous except for T1-2N0 lesions of E7. This was related to the introduction of histologic grade in E7 staging. Distinctiveness in each staging system was variable. As for the homogeneity, patients whose disease was staged as Ib (E7) exhibited different survival when reassessed by G6 and G7; again, this was related to histologic grading. Patients with IIIb (G7) and IIIc (E7) disease had different survival when reassessed by G6 staging, reflecting the poorer survival of patients with more than 15 lymph node metastases. Conclusions: Staging of EGJ cancer based on the current AJCC, 7th edition, criteria of esophageal cancer staging has several limitations. We recommend considering modifications of the following in future updates of the staging system: accurate anatomical definition of tumor depth, removal of histologic grade from staging parameters, and classification of more than 15 lymph node metastases as a highly advanced stage.
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