1. Department of Gastroenterological Surgery I, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
2. Division of Hepato-Biliary-Pancreatic and Transplant Surgery, Department of Surgery, Asahikawa Medical University, Asahikawa, Japan
3. Department of Gastroenterology and Hepatology, Graduate School of Medicine, Hokkaido University, Sapporo, Japan