1. Department of Surgery, Gastroenterological Center Yokohama City University Medical Center Yokohama Japan
2. Department of Surgery Yokosuka Kyosai Hospital Yokosuka Japan
3. Department of Gastroenterological Surgery Yokohama City University Graduate School of Medicine Yokohama Japan
4. Department of Surgery NTT Medical Center Tokyo Tokyo Japan
5. Department of Surgery Yokosuka City Hospital Yokosuka Japan
6. Department of Surgery Fujisawa City Hospital Fujisawa Japan
7. Department of Surgery Yokohama City Minato Red Cross Hospital Yokohama Japan
8. Department of Surgery Saiseikai Yokohamashi Nanbu Hospital Yokohama Japan
9. Department of Surgery National Hospital Organization Yokohama Medical Center Yokohama Japan
10. Department of Biostatistics Yokohama City University Graduate School of Medicine Yokohama Japan