1. Department of HBP and Breast Surgery; Ehime University; Ehime Japan
2. Department of Surgery; Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital; Tokyo Japan
3. Department of Surgery; Yamaga City Medical Center; Kumamoto Japan
4. Department of Colorectal Surgery; Tochigi Cancer Center; Tochigi Japan
5. Department of Surgery; Institute of Gastroenterology; Tokyo Women's Medical University; Tokyo Japan
6. Department of Gastroenterological Surgery; Yokohama City University Graduate School of Medicine; Kanagawa Japan
7. Hepato-Biliary-Pancreatic Surgery Division; Department of Surgery; Graduate School of Medicine; The University of Tokyo; Tokyo Japan
8. Department of Surgery; Teikyo University School of Medicine; Tokyo Japan
9. Department of Hepatobiliary and Pancreatic Surgery; National Cancer Center Hospital East; Chiba Japan
10. Department of Biomedical Statistics and Bioinformatics; Graduate School of Medicine; Kyoto University; Kyoto Japan
11. Department of General Surgery; Chiba University; Chiba Japan
12. Koujinkai Daiichi Hospital; Tokyo Japan