1. Department of Gastroenterological, Breast and Endocrine Surgery, Yamaguchi University Graduate School of Medicine, Ube, Yamaguchi 755‑8505, Japan
2. Department of Digestive Surgery, Osaka International Cancer Institute, Osaka 541‑8567, Japan
3. Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, Osaka 565‑0871, Japan
4. Department of Digestive Surgery, Kawasaki Medical School, Kurashiki, Okayama 701‑0192, Japan