1. Division of Colon and Rectal Surgery, Shizuoka Cancer Center Hospital, Shizuoka, Japan.
2. Arakawa Clinic of Proctology, Tokyo, Japan.
3. Department of Anatomy, Akita University School of Medicine, Akita, Japan.
4. Oral Health Science Center hrc8, Tokyo Dental College, Chiba, Japan.
5. Department of Surgery, Chonbuk National University School of Medicine, Jeonju, Korea.
6. Division of Internal Medicine, Iwamizawa Kojin-kai Hospital, Iwamizawa, Japan.
7. Department of Surgical Oncology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.