1. Department of Hepatobiliary and Pancreatic Oncology, National Cancer Center Hospital, Tokyo, Japan
2. Department of Hepatobiliary and Pancreatic Oncology, National Cancer Center Hospital East, Kashiwa, Japan
3. Department of Gastroenterology, Chiba Cancer Center, Chiba, Japan
4. Department of Medical Oncology, Kyorin University Faculty of Medicine, Tokyo, Japan