Yasuo Hamamoto1, Tatsuro Yamaguchi2, Tomohiro Nishina3, Kentaro Yamazaki4, Takashi Ura5, Takako Nakajima6, Ayumu Goto7, Ken Shimada8, Norisuke Nakayama9, Junichi Sakamoto10, Satoshi Morita11, Yasuhide Yamada12. 1. Keio Cancer Center, School of Medicine, Keio University, Tokyo, Japan; yhamamoto@z2.keio.jp yayamada@ncc.go.jp. 2. Department of Surgery, Tokyo Metropolitan Cancer and Infectious Disease Center, Komagome Hospital, Tokyo, Japan; 3. Department of Gastrointestinal Medical Oncology, National Hospital Organization Shikoku Cancer Center, Ehime, Japan; 4. Division of Gastrointestinal Oncology, Shizuoka Cancer Center, Shizuoka, Japan; 5. Department of Clinical Oncology, Aichi Cancer Center Central Hospital, Nagoya, Japan; 6. Department of Medical Oncology, St. Marianna University School of Medicine, Kanagawa, Japan; 7. Department of Clinical Oncology, Yokohama City University Hospital, Kanagawa, Japan; 8. Department of Medical Oncology, Showa University Northern Yokohama Hospital, Kanagawa, Japan; 9. Department of Gastroenterology, Kanagawa Cancer Center Hospital, Kanagawa, Japan; 10. Director, Tokai Central Hospital, Gifu, Japan; 11. Department of Biostatistics and Epidemiology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; 12. Gastrointestinal Oncology Division, National Cancer Center Hospital, Tokyo, Japan yhamamoto@z2.keio.jp yayamada@ncc.go.jp.