1. Gastroenterology, Toyoshima Endoscopy Clinic, Tokyo, Japan
2. Department of Gastroenterology and Hepatology, International University of Health and Welfare Narita Hospital, Chiba, Japan
3. Pathology and Cytology Laboratory Japan, Tokyo, Suginami, Japan
4. Department of Gastroenterology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
5. Endoscopy Division, National Cancer Center Hospital, Tokyo, Japan