1. Department of Surgery Yamaga City Medical Center Yamaga Japan
2. Department of Gastroenterological Surgery Graduate School of Life Sciences Kumamoto University Kumamoto Japan
3. Department of Gastroenterological Surgery New Tokyo Hospital Matsudo Japan
4. Department of Hepato‐Biliary‐Pancreatic and Breast Surgery Ehime University Graduate School of Medicine Toon Japan
5. Department of Hepatobiliary and Pancreatic Surgery National Cancer Center Hospital East Kashiwa Japan
6. Department of Gastroenterological Surgery Yokohama City University Graduate School of Medicine Yokohama Japan
7. Hepato‐Biliary‐Pancreatic Surgery Division Department of Surgery Graduate School of Medicine University of Tokyo Bunkyo‐ku Japan
8. Department of Surgery Sano City Hospital Sano Japan
9. Department of Surgery Institute of Gastroenterology Tokyo Women’s Medical University Shinjuku‐ku Japan
10. Department of Surgery Teikyo University Graduate School of Medicine Itabashi‐ku Japan
11. Department of Surgery Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital Bunkyo‐ku Japan
12. Department of Pediatrics Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital Bunkyo‐ku Japan
13. Department of Surgery Teikyo University Hospital Mizonokuchi Japan
14. Department of Gastroenterological Chemotherapy Cancer Institute Hospital of Japanese Foundation for Cancer Research Tokyo Japan
15. Department of Biomedical Statistics and Bioinformatics Graduate School of Medicine Kyoto University Kyoto Japan
16. Sakurajuji Hospital Kumamoto Japan
17. International University of Health and WelfareMita Hospital Minata‐ku Japan
18. Tokyo Medical and Dental University Bunkyo‐ku Japan