1. Department of Surgery, Keio University School of Medicine, Tokyo, Japan
2. Department of Health Policy and Management, Keio University School of Medicine, Tokyo, Japan
3. Department of Surgery, Tokyo Dental College Ichikawa General Hospital, Ichikawa, Japan
4. Department of Gastroenterological Surgery, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
5. Department of Gastroenterological and Pediatric Surgery, Faculty of Medicine, Oita University, Yufu, Japan
6. Department of Surgery, Ageo Central General Hospital, Ageo, Japan
7. Division of Gastrointestinal Surgery, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan
8. Database Committee, The Japanese Society of Gastroenterological Surgery
9. The Japanese Society of Gastroenterological Surgery
10. Department of Surgery, Kitasato University Kitasato Institute Hospital, Sagamihara, Japan