1. Division of Hepatobiliary and Pancreatic Oncology, Kanagawa Cancer Center , Yokohama , Japan
2. Department of Gastroenterology, Internal Medicine, Kitasato University School of Medicine , Sagamihara , Japan
3. Gastroenterological Center, Yokohama City University Medical Center , Yokohama , Japan
4. Division of Gastroenterology and Hepatology, Department of Internal Medicine, Tokai University School of Medicine , Isehara , Japan
5. Division of Gastroenterology and Hepatology, Department of Internal Medicine, St. Marianna University School of Medicine , Kawasaki , Japan
6. Gastroenterology Division, Hadano Red Cross Hospital , Hadano , Japan
7. Department of Gastroenterology, Yokohama City University Graduate School of Medicine , Yokohama , Japan