National Defense Medical College - Department of Surgery, National Defense Medical College, Shizuoka Cancer Center Hospital, Kanagawa Cancer Center, National Cancer Center Hospital East - Department of Colorectal Surgery, Yamagata Prefectural Central Hospital, Department of Surgery, Teikyo University School of Medicine, Keiyukai Sapporo Hospital, Tokyo Medical and Dental University, Department of Surgery, Saisei-kai Yokohama-shi Nanbu Hospital, Wakayama Medical University, Takano Hospital, Aichi Cancer Center, Department of Surgery, Tokyo Metropolitan Cancer and Infectious diseases Center Komagome Hospital, National Cancer Center Hospital, Department of Surgery, Tochigi Cancer Centre, Colorectal and Pelvic Surgery Division, Department of Surgical Oncology, National Cancer Center Hospital East, Kyorin University - Department of Surgery, Department of Surgery, Yamagata Prefectural Central Hospital, Department of Gastroenterological Surgery, Yokohama City University Graduate School of Medicine, Department of Surgery, Gastroenterological Centre, Yokohama City University Medical Centre, Mie University - Department of Gastrointestinal and Pediatric Surgery, Shiga University of Medical Science, Department of Surgery, Teikyo University Chiba Medical Centre, Kurume University - Kurume University Hospital, Department of Surgery, Institute of Gastroenterology, Tokyo Women's Medical University, National Defense Medical College and Tokyo Medical and Dental University