Tatsuya Orimo1, Toshiya Kamiyama2, Akinobu Taketomi2. 1. Department of Gastroenterological Surgery I, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan. kaorioritatsu@ybb.ne.jp. 2. Department of Gastroenterological Surgery I, Hokkaido University Graduate School of Medicine, Sapporo, Hokkaido, Japan.