Conducting clinical trials to establish evidence of the benefits of adjuvant treatment for resectable esophagogastric junction (EGJ) cancer is difficult because it is a very rare disease compared with gastric or esophageal cancer. In the West, where esophageal cancer occurs more frequently than gastric cancer, a phase III trial (the CROSS trial) demonstrated the efficacy of preoperative chemoradiotherapy using carboplatin plus paclitaxel for patients with esophageal or EGJ cancer. Thus, this preoperative regimen is considered to be the standard adjuvant treatment for resectable EGJ cancer in the West. On the other hand, the Western evidence is not widely accepted in Asia because there are many differences in surgical techniques, particularly in the field of lymph node dissection, between the West and Asia. The standard adjuvant treatment for resectable EGJ cancer in Asia is postoperative chemotherapy using S-1 alone or capecitabine plus oxaliplatin based on the results of two large-scale phase III trials in gastric cancer conducted in East Asia. The incidence of EGJ cancer has recently increased in Japan, and nationwide studies to develop more effective adjuvant treatment for resectable EGJ cancer should be conducted in the near future.