1. Gastroenterological Center; Yokohama City University Medical Center; Yokohama Japan
2. Department of Hepatobiliary and Pancreatic Medical Oncology; Kanagawa Cancer Center; Yokohama Japan
3. Department of Gastroenterology; Internal Medicine; Kitasato University School of Medicine; Sagamihara Japan
4. Division of Gastroenterology and Hepatology; Department of Internal Medicine; St Marianna University School of Medicine; Kawasaki Japan
5. Department of Biostatistics and Epidemiology; Yokohama City University Medical Center; Yokohama Japan