Y Tashiro1,2, M Murakami3, Y Fukoe4, Y Lee4, M Lee4. 1. Department of Gastroenterological Surgery, Shiroyama Hospital, 1 Iizuka-cho, Ota, Gunma, 373-0817, Japan. ytashiro@showa-u.med.ac.jp. 2. Department of General and Gastroenterological Surgery, Showa University School of Medicine, Tokyo, 142-8666, Japan. ytashiro@showa-u.med.ac.jp. 3. Department of General and Gastroenterological Surgery, Showa University School of Medicine, Tokyo, 142-8666, Japan. 4. Department of Gastroenterological Surgery, Shiroyama Hospital, 1 Iizuka-cho, Ota, Gunma, 373-0817, Japan.