1. Department of Gastroenterological Surgery I, Graduate School of Medicine, Hokkaido University, Hokkaido, Japan
2. Department of Surgery, Sunagawa City Medical Centre, Sunagawa, Japan
3. Department of Surgery, Asahikawa-Kosei General Hospital, Asahikawa, Japan
4. Department of Gastrointestinal Surgery, National Hospital Organization Hokkaido Cancer Centre, Hokkaido
5. Surgical Centre, Hokkaido, Japan
6. Clinical Research and Medical Innovation Centre, Hokkaido University Hospital, Hokkaido, Japan