1. Gastroenterology, Toyoshima Endoscopy Clinic, Tokyo, Japan
2. Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokoyo, Japan
3. Department of Gastroenterology and Hepatology, International University of Health and Welfare, Mita Hospital, Tokyo, Japan
4. Department of Gastroenterology, Sanraku Hospital, Chiyoda-ku, Japan
5. Department of Surgical Oncology, Graduate School of Medicine, The University of Tokyo, Japan
6. Pathology and Cytology Laboratory Japan, Tokyo, Japan