1. Department of Gastroenterology and Hepatology, Uonuma Institute of Community Medicine Niigata University Hospital, Japan
2. Division of Hepatobiliary and Pancreatic Surgery, National Cancer Center Hospital, Japan
3. Department of Surgery, National Defense Medical College, Japan
4. Division of Pathology and Clinical Laboratories, National Cancer Center Hospital, Japan
5. Department of Pathology, Uonuma institute of Community Medicine Niigata University Hospital, Japan
6. Department of Pathology, Nagaoka Central General Hospital, Japan
7. Division of Gastroenterology and Hepatology, Graduate School of Medical and Dental Sciences, Niigata University, Japan