1. Department of Gastroenterology, SAPPORO MEDICAL CENTER NTT EC, Nippon Telegraph and Telephone East Corporation, Japan
2. Department of Cancer Preventive Medicine, Hokkaido University Graduate School of Medicine, Japan
3. Department of Pathology, SAPPORO MEDICAL CENTER NTT EC, Nippon Telegraph and Telephone East Corporation, Japan
4. School of Pharmaceutical Sciences, Kitasato University, Japan
5. Department of Gastroenterology, Sapporo City General Hospital, Japan
6. Division of Endoscopy, Hokkaido University Hospital, Japan
7. Department of Gastroenterology and Hepatology, Hokkaido University Graduate School of Medicine, Japan