1. Digestive Disease Center Showa University Northern Yokohama Hospital Yokohama Japan
2. Department of Gastroenterological and Pediatric Surgery Oita University Oita Japan
3. Hiroshima City North Medical Center Asa Citizens Hospital Hiroshima Japan
4. Department of Surgery Southern Tohoku General Hospital Koriyama Japan
5. Department of Digestive and General Surgery Juntendo University Urayasu Hospital Urayasu Japan
6. Department of Surgery National Hospital Organization Nagasaki Medical Center Nagasaki Japan
7. Department of Gastroenterological Surgery Niigata Cancer Center Hospital Niigata Japan
8. Department of Surgery Nagano Municipal Hospital Nagano Japan
9. Department of Gastroenterological Surgery I, Graduate School of Medicine Hokkaido University Sapporo Japan
10. Department of Surgery Kyoto University Hospital Kyoto Japan
11. Division of Colorectal Surgery, Department of Surgery Tokyo Women's Medical University Tokyo Japan
12. Department of Lower Gastrointestinal Surgery Kitasato University School of Medicine Sagamihara Japan