National Cancer Center Hospital - Gastrointestinal Medical Oncology Division, National Cancer Center Hospital, Showa University, National Cancer Center Hospital, Tokai University, Kanagawa Cancer Center - Department of Gastrointestinal Surgery, Saitama Cancer Center, Aichi Cancer Center, Aichi Cancer Center, Niigata Cancer Center Hospital, Shizuoka General Hospital, Keio University, Kochi University - Kochi Health Sciences Center, Shizuoka Cancer Center, Hyogo Cancer Center, Shikoku Cancer Centre, Kumamoto University - Department of Gastroenterological Surgery, Toranomon Hospital, Hamamatsu University, National Cancer Center Hospital, Keio University - Department of Surgery and Independent