1. Department of Medical Oncology, Sapporo Medical University School of Medicine , Sapporo , Japan
2. Department of Medical Genetics and Genomics, Sapporo Medical University School of Medicine , Sapporo , Japan
3. Department of Gastroenterology and Hepatology, Sapporo Medical University School of Medicine , Sapporo , Japan
4. Department of Gastroenterology, Hokkaido Cancer Center , Sapporo , Japan
5. Department of Gastroenterology, Oji General Hospital , Tomakomai , Japan
6. Department of Medical Oncology, Steel Memorial Muroran Hospital , Muroran , Japan
7. Department of Gastroenterology, Steel Memorial Muroran Hospital , Muroran , Japan
8. Department of Gastroenterology, Otaru Ekisaikai Hospital , Otaru , Japan
9. Department of Gastroenterology, Japanese Red Cross Date Hospital , Date , Japan
10. Department of Gastroenterology, Rumoi City Hospital , Rumoi , Japan
11. Department of Gastroenterology, Hakodate Goryoukaku Hospital , Hakodate , Japan