1. Department of Hepatobiliary–Pancreatic and Gastrointestinal Surgery, International University of Health and Welfare School of Medicine , Chiba , Japan
2. Department of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo , Tokyo , Japan
3. Department of Cardiovascular Medicine, The University of Tokyo , Tokyo , Japan
4. Department of Surgery, Keio University School of Medicine , Tokyo , Japan
5. Department of Health Policy and Informatics, Tokyo Medical and Dental University Graduate School , Tokyo , Japan
6. Division of Esophageal Surgery, National Cancer Center Hospital , Tokyo , Japan