1. Department of Gastroenterology; Tomakomai City Hospital; Tomakomai Hokkaido Japan
2. Department of Gastroenterology and Hepatology; Hokkaido University Hospital; Kita 14, Nishi 5, Kita-ku Sapporo Hokkaido 060-8648 Japan
3. Department of Gastroenterology; NTT East Japan Sapporo Hospital; Sapporo Hokkaido Japan
4. Department of Gastroenterology; Municipal Hakodate Hospital; Hakodate Hokkaido Japan
5. Department of Gastroenterology; Oji General Hospital; Tomakomai Hokkaido Japan
6. Center for Gastroenterology; Teine-Keijinkai Hospital; Sapporo Hokkaido Japan
7. Department of Medical Oncology and Hematology; Sapporo Medical University Hospital; Sapporo Hokkaido Japan
8. Department of Gastroenterology; Japanese Red Cross Kitami Hospital; Kitami Japan
9. Department of Internal Medicine and Gastroenterology; Abashiri-Kosei General Hospital; Abashiri Hokkaido Japan
10. Third Department of Internal Medicine; Obihiro Kosei General Hospital; Obihiro Hokkaido Japan
11. Gastroenterology Center; Sapporo Higashi Tokushukai Hospital; Sapporo Hokkaido Japan
12. Department of Gastroenterology; Sapporo Hokushin Hospital; Sapporo Hokkaido Japan
13. Department of Gastroenterology and Hepatology; Hokkaido University Graduate School of Medicine; Sapporo Hokkaido Japan