1. Department of Surgery Kyoto University Graduate School of Medicine Kyoto Japan
2. Department of Surgery National Hospital Organization Kyoto Medical Center Kyoto Japan
3. Department of Surgery Kyoto Katsura Hospital Kyoto Japan
4. Department of Surgery Shiga General Hospital Morinomiya Japan
5. Department of Gastrointestinal Surgery Tenri Hospital Tenri Japan
6. Department of Surgery Osaka Red Cross Hospital Osaka Japan
7. Department of Surgery Kobe City Medical Center General Hospital Kobe Japan
8. Department of Surgery Kitano Hospital Osaka Japan
9. Department of Surgery Shimane Prefectural Central Hospital Izumo Japan
10. Department of Biomedical Statistics and Bioinformatics Kyoto University Graduate School of Medicine Kyoto Japan