1. Department of Gastroenterological Surgery Yokohama City University Graduate School of Medicine Yokohama Japan
2. Department of Surgery, Gastroenterological Center Yokohama City University Medical Center Yokohama Japan
3. Department of Surgery Yokosuka Kyousai Hospital Yokosuka Japan
4. Department of Surgery Yokohama City Minato Red Cross Hospital Yokohama Japan
5. Department of Surgery Fujisawa City Hospital Fujisawa Japan
6. Department of Surgery NTT Medical Center Tokyo Tokyo Japan
7. Department of Surgery Yokohama Medical Center Yokohama Japan