Mitsuaki Ishioka1, Toshiaki Hirasawa1, Tomohiro Tada2,3,4. 1. Department of Gastroenterology, Cancer Institute Hospital, Japanese Foundation for Cancer Research, Tokyo, Japan. 2. AI Medical Service Inc., Tokyo, Japan. 3. Department of Surgical Oncology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan. 4. Tada Tomohiro Institute of Gastroenterology and Proctology, Saitama, Japan.