1. Department of Surgery, Faculty of Medicine Nara Hospital, Kindai University Ikoma Japan
2. Hepato‐Biliary‐Pancreatic Group Clinical Study Group of Osaka University Osaka Japan
3. Department of Surgery Toyonaka Municipal Hospital Toyonaka Japan
4. Department of Gastroenterological Surgery Graduate School of Medicine, Osaka University Suita Japan
5. Department of Surgery Suita Municipal Hospital Suita Japan
6. Department of Surgery Hyogo Prefectural Nishinomiya Hospital Nishinomiya Japan
7. Department of Surgery Tane General Hospital Osaka Japan
8. Department of Surgery Osaka Police Hospital Osaka Japan
9. Department of Surgery Rinku General Medical Center Osaka Japan
10. Department of Surgery Japan Community Health Care Organization, Osaka Hospital Osaka Japan
11. Department of Surgery Kansai Rosai Hospital Amagasaki Japan
12. Department of Surgery Osaka Rosai Hospital Sakai Japan
13. Department of Surgery Higashiosaka City Medical Center Higashiosaka Japan
14. Department of Surgery National Hospital Organization Osaka National Hospital Osaka Japan
15. Department of Surgery Sakai City Medical Center Sakai Japan
16. Department of Surgery Yao Municipal Hospital Yao Japan
17. Department of Surgery Ashiya Municipal Hospital Ashiya Japan
18. Department of Surgery Minoh City Hospital Minoh Japan
19. Department of Surgery Kawanishi City Hospital Kawanishi Japan
20. Department of Surgery Osaka General Medical Center Osaka Japan
21. Department of Surgery Otemae Hospital Osaka Japan