1. Division of Surgery Gastrointestinal Center Yokohama Shin‐Midori General Hospital Yokohama Japan
2. Department of Gastroenterological and Pediatric Surgery Oita University Faculty of Medicine Oita Japan
3. Japan Clinical Oncology Group Data Center/Operations Office National Cancer Center Hospital Tokyo Japan
4. Department of Surgery Tokai University School of Medicine Kanagawa Japan
5. Department of Colorectal Surgery National Cancer Center Hospital East Chiba Japan
6. Department of Gastrointestinal Surgery Tokyo Medical and Dental University Tokyo Japan
7. Department of Gastrointestinal Surgery and Surgical Oncology Ehime University Graduate School of Medicine Ehime Japan
8. Department of Surgery Nagano Municipal Hospital Nagano Japan
9. Department of Gastroenterological Surgery St. Marianna University Yokohama Seibu Hospital Yokohama Japan
10. Department of Gastroenterological Surgery Ishikawa Prefectural Central Hospital Kanazawa Japan
11. Department of Gastroenterological Surgery Osaka International Cancer Institute Osaka Japan
12. Division of Lower Gastrointestinal Surgery, Department of Gastroenterological Surgery Hyogo College of Medicine Nishinomiya Japan
13. Department of Surgery NTT Medical Center Tokyo Japan
14. Division of Frontier Surgery The Institute of Medical ScienceThe University of Tokyo Tokyo Japan
15. Department of Colorectal Surgery National Cancer Center Hospital Tokyo Japan
16. Oita University Oita Japan