1Department of Surgery, Shikoku Cancer Center Hospital, 160 Minami-umemoto, Matsuyama, 791-0280 Japan
2Department of Gastrointestinal Medical Oncology, National Cancer Center Hospital, Tokyo, Japan
3Department of Esophageal Surgery, National Cancer Center Hospital, Tokyo, Japan
4Department of Radiation Oncology, National Cancer Center Hospital, Tokyo, Japan
5Department of Esophageal Surgery, National Cancer Center Hospital East, Chiba, Japan
6Department of Surgery, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, Japan
7Department of Gastroenterological Surgery, Toranomon Hospital, Tokyo, Japan
8JCOG Data Center/Operations Office, Center for Research Administration and Support, National Cancer Center, Tokyo, Japan
9Department of Surgery, Keio University School of Medicine, Tokyo, Japan