Wakayama Medical University - Second Department of Surgery, Wakayama Medical University - Clinical Study Support Centre, Tokyo Medical University, Tokyo Medical University, Wakayama Medical University - Second Department of Surgery, Kindai University - Department of Surgery, Kansai Medical University - Department of Surgery, Chiba University, Kochi University - Kochi Health Sciences Center, Tohoku University, Osaka City University, Hiroshima University, Hokkaido University, Kurashiki Central Hospital, National Hospital Organization (NHO) - Osaka National Hospital, National Cheng Kung University - Institute of Clinical Medicine, St. Marianna University, Iwate Medical University, Hiroshima City Hiroshima Citizens Hospital, Osaka Medical College - Department of General and Gastroenterological Surgery, Chang Gung University - Chang Gung Memorial Hospital, Nagaoka Chuo General Hospital, Tohoku University - Graduate School of Medicine, Chang Gung University - Chang Gung Memorial Hospital and Wakayama Medical University - Second Department of Surgery