1. Department of Surgery, Kyushu University Beppu Hospital, Beppu, Oita 874‑0838, Japan
2. Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, Suita, Osaka 565‑0871, Japan
3. Department of Gastroenterological Surgery, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 860‑8556, Japan