1. Department of Gastroenterology, Graduate School of Medicine; University of Tokyo; Tokyo Japan
2. Department of Gastroenterology; Tokatsu-Tsujinaka Hospital; Chiba Japan
3. Department of Gastroenterology; Kanto Central Hospital; Tokyo Japan
4. Institute for Adult Disease, Asahi Life Foundation; Tokyo Japan
5. Department of Gastroenterology; Japanese Red Cross Medical Center; Tokyo Japan
6. Kyoundo Hospital; Tokyo Japan
7. Department of Gastroenterology; JR Tokyo General Hospital; Tokyo Japan
8. Wakamiyawatabe Clinic; Chiba Japan
9. Department of Gastroenterology; Teikyo University Chiba Medical Center; Chiba Japan
10. Department of Gastroenterology; Sanno Medical Center; Tokyo Japan
11. Takano Clinic; Tokyo Japan
12. Center for Cancer Control and Statistics; Osaka Medical Center for Cancer and Cardiovascular Diseases; Osaka Japan