1. Hepato-Biliary-Pancreatic Surgery Division; Department of Surgery, Graduate School of Medicine, University of Tokyo; Tokyo Japan
2. Division of Gastroenterological Surgery; Saitama Cancer Center; Saitama Japan
3. Department of Biostatistics; School of Public Health, University of Tokyo; Tokyo Japan
4. Department of Digestive Surgery; Nihon University School of Medicine; Tokyo Japan
5. Department of Gastroenterology; Musashino Red Cross Hospital; Tokyo Japan
6. Department of Radiology; Shinshu University School of Medicine; Matsumoto Japan
7. Department of Gastroenterology and Hepatology; Kinki University School of Medicine; Osaka Japan
8. Department of Hepato-Biliary-Pancreatic Surgery; Osaka City University Graduate School of Medicine; Osaka Japan
9. Department of Pathology; Keio University School of Medicine; Tokyo Japan
10. Department of Clinical Laboratory Medicine; Kurume University Hospital; Kurume Japan
11. Department of Gastroenterology; Ogaki Municipal Hospital; Ogaki Japan