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

Nagoya University Graduate School of Medicine - Department of Gastroenterological Surgery (Surgery II), University of Toyama - Department of Surgery and Science, Nagoya University Graduate School of Medicine - Department of Gastroenterological Surgery (Surgery II), Wakayama Medical University - Second Department of Surgery, University of Toyama - Department of Surgery and Science, Kindai University - Department of Surgery, Oita Red Cross Hospital - Department of Surgery, Kumamoto University - Department of Gastroenterological Surgery, Showa University - Department of Gastroenterological and General Surgery, Tohoku University Graduate School of Medicine - Division of Hepato-Biliary Pancreatic Surgery, Kansai Medical University - Department of Surgery, National Defense Medical College - Department of Surgery, Hyogo College of Medicine - Department of Gastroenterological Surgery, Hiroshima University Graduate School of Biomedical and Health Sciences - Department of Surgery, Fujita Health University - Bantane Hospital, Department of Gastroenterological Surgery, Nara Medical University School of Medicine - Department of Surgery, Kansai Rosai Hospital - Japan Organization of Occupational Health and Safety, Department of Surgery, Wakayama Medical University - Clinical Study Support Centre, Nagoya University Graduate School of Medicine - Department of Gastroenterological Surgery (Surgery II) and Wakayama Medical University - Second Department of Surgery