1. Division of Hepatobiliary and Pancreatic Surgery Department of General Surgical Science Graduate School of Medicine Gunma University Maebashi Japan
2. Department of Innovative Cancer Immunotherapy Graduate School of Medicine Gunma University Maebashi Japan
3. Department of Legal Medicine Graduate School of Medicine Gunma University Maebashi Japan
4. Department of Gastroenterological Surgery Graduate School of Medicine Osaka University Suita Japan
5. Department of Gastroenterological Surgery Graduate School of Life Sciences Kumamoto University Kumamoto Japan
6. Department of Surgery and Science Faculty of Medicine, Academic Assembly University of Toyama Toyama Japan
7. Department of Gastroenterological Surgery (Surgery II) Nagoya University Graduate School of Medicine Nagoya Japan
8. Department of Biostatistics Yamaguchi University Graduate School of Medicine Yamaguchi Japan