1. Colorectal Surgery Division, National Cancer Center Hospital, 5-1-1 Tsukiji, Chuo-ku, Tokyo, Japan
2. Gastrointestinal Medical Oncology Division, Saitama Medical University International Medical Center, Hidaka City, Saitama, Japan
3. Gastrointestinal Medical Oncology Division, Kochi Health Sciences Center, Kochi City, Kochi, Japan