1. The Japan Society for Endoscopic Surgery Tokyo Japan
2. Department of Surgery Kobe University Graduate School of Medicine Kobe Japan
3. Department of Healthcare Quality Assessment Graduate School of Medicine The University of Tokyo Tokyo Japan
4. Department of Gastroenterological and Pediatric Surgery Oita University Faculty of Medicine Yufu City Japan
5. The Japanese Society of Gastroenterological Surgery Tokyo Japan
6. Department of Surgery Graduate School of Medicine Kyoto University Kyoto Japan
7. The Japanese Society of Gastroenterological Surgery Database Committee Tokyo Japan
8. Department of Surgery Keio University School of Medicine Tokyo Japan
9. Department of Surgery Kitasato Institute Hospital Tokyo Japan