1. Department of Surgery Kochi Medical School Kochi Japan
2. Department of Healthcare Quality Assessment, Graduate School of Medicine The University of Tokyo Tokyo Japan
3. Department of Gastroenterological Surgery I Hokkaido University Hospital Hokkaido Japan
4. Database Committee, The Japanese Society of Gastroenterological Surgery Tokyo Japan
5. Department of Gastrointestinal Surgery, Graduate School of Medicine The University of Tokyo Tokyo Japan
6. Department of Gastroenterological and Pediatric Surgery, Graduate School of Medicine Gifu University Gifu Japan
7. Second Department of Surgery, School of Medicine Wakayama Medical University Wakayama Japan
8. Utsunomiya Memorial Hospital Tochigi Japan
9. The Japanese Society of Gastroenterological Surgery, Tokyo, Japan & Department of Surgery Keio University School of Medicine Tokyo Japan
10. School of Medicine Tokai University Kanagawa Japan
11. Kochi Medical School Hospital Kochi Japan