1. Department of Gastroenterological Surgery, Kagawa University, Kagawa, Japan
2. Department of Public Health, Faculty of Medicine, Kagawa University, Kagawa, Japan
3. Department of Surgery, Graduate School of Medicine, Tohoku University, Sendai, Japan
4. Department of Gastroenterological Surgery (Surgery II), Nagoya University Graduate School of Medicine, Nagoya, Japan
5. Department of General Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan
6. Department of Gastroenterological Surgery, Tokyo Women's Medical University, Tokyo, Japan
7. Department of Surgery, Kansai Medical University, Hirakata, Japan
8. Department of Hepato-Biliary Pancreatic Surgery, National Cancer Centre Hospital East, Kashiwa, Japan
9. Department of Gastroenterological Surgery, Chiba Cancer Centre, Chiba, Japan