1. Department of Surgery Hamamatsu University School of Medicine Hamamatsu Japan
2. Department of Healthcare Quality Assessment The University of Tokyo Tokyo Japan
3. Department of Gastroenterological Surgery Tokai University School of Medicine Isehara Japan
4. Division of Gastrointestinal Surgery, Department of Surgery, Graduate School of Medicine Kobe University Kobe Japan
5. Database Committee The Japanese Society of Gastroenterological Surgery Tokyo Japan
6. Department of Frontier Surgery Chiba University Graduate School of Medicine Chiba Japan
7. The Japan Esophageal Society Tokyo Japan
8. Department of Gastroenterological Surgery Osaka University Graduate School of Medicine Osaka Japan
9. Department of Surgery Keio University School of Medicine Tokyo Japan
10. The Japanese Society of Gastroenterological Surgery Tokyo Japan