1. Department of Surgery, Graduate School of Medicine, Osaka University, Suita, Japan
2. Department of Surgery, Japan Community Health Care Organization Osaka Hospital, Osaka, Japan
3. Department of Gastroenterological Surgery, Kawasaki Medical School Hospital, Kurashiki, Japan
4. Department of Surgery, Osaka Police Hospital, Osaka, Japan
5. Department of Surgery, Kindai University Nara Hospital, Ikoma, Japan
6. Department of Gastroenterological Surgery, Osaka General Medical Center, Osaka, Japan