1. Japanese Society of Hepato‐Biliary‐Pancreatic Surgery Tokyo Japan
2. Department of Surgery and Oncology Graduate School of Medical Sciences Kyushu University 3-1-1 Maidashi Fukuoka 812-8582 Japan
3. Department of Healthcare Quality Assessment Graduate School of Medicine The University of Tokyo Tokyo Japan
4. Database Committee The Japanese Society of Gastroenterological Surgery Tokyo Japan
5. The Japanese Society of Gastroenterological Surgery Tokyo Japan
6. Second Department of Surgery School of Medicine Wakayama Medical University Wakayama Japan
7. Department of Surgery Institute of Gastroenterology Tokyo Women's Medical University Tokyo Japan