1. Department of Surgical Oncology, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan
2. Department of Surgical Oncology, The University of Tokyo, Tokyo, Japan
3. Department of Hepatobiliary and Pancreatic Surgery, The University of Tokyo, Tokyo, Japan
4. Department of Thoracic Surgery, The University of Tokyo, Tokyo, Japan