1. Department of Medical Oncology and Hematology, Sapporo Medical University, Sapporo, Japan
2. Department of Gastroenterology and Hepatology, Hokkaido University Hospital, Sapporo, Japan
3. Department of Gastroenterology, Japanese Red Cross Date General Hospital, Date, Japan
4. Center for Gastroenterology, Teine-Keijinkai Hospital, Sapporo, Japan
5. Department of Gastroenterology, Abashiri-Kosei General Hospital, Abashiri, Japan
6. Department of Gastroenterology, Tomakomai City Hospital, Tomakomai, Japan
7. Department of Gastroenterology, NTT East Japan Sapporo Hospital, Sapporo, Japan
8. Department of Gastroenterology, Oji General Hospital, Tomakomai, Japan
9. Department of Gastroenterology, KKR Sapporo Medical Center Tonan Hospital, Sapporo, Japan
10. Department of Gastroenterology, Rumoi City Hospital, Rumoi, Japan
11. Department of Gastroenterology, Obihiro-Kosei General Hospital, Obihiro, Japan
12. Department of Gastroenterology, Otaru Ekisaikai Hospital, Otaru, Japan
13. Department of Public Health, Sapporo Medical University School of Medicine, Sapporo, Japan