1. Department of Surgery, National Center for Global Health and Medicine; Tokyo, Japan.
2. The Research Center for Hepatitis and Immunology Department of Diseases, National Center for Global Health and Medicine, Tokyo, Japan.
3. Department of Gastroenterology, The University of Tokyo, Tokyo, Japan.
4. Department of Surgical Pathology, National Center for Global Health and Medicine, Tokyo, Japan.
5. Department of Surgery, Division of Hepatobiliary Pancreatic Surgery, The University of Tokyo, Tokyo, Japan.