1. Department of Gastrointestinal Surgery, Kanagawa Cancer Center, Yokohama, Kanagawa 241‑8515, Japan
2. Department of Gastroenterological Surgery, Cancer Institute Hospital of Japanese Foundation for Cancer Research, Tokyo 135‑0063, Japan
3. Department of Biostatistics and Epidemiology, Yokohama City University Medical Center, Yokohama, Kanagawa 232‑0024, Japan
4. Department of Gastroenterological Surgery, Aichi Cancer Center, Nagoya, Aichi 464‑8681, Japan
5. Department of Surgery, Osaka General Medical Center, Osaka 558‑8558, Japan
6. Division of Gastroenterological Surgery, Chiba Cancer Center, Chuo-ku, Chiba 260‑8781, Japan
7. Department of Gastroenterological Surgery, Saitama Cancer Center, Kitaadachi, Saitama 362‑0806, Japan
8. Department of Surgery, Osaka Medical Center, Osaka 540‑0006, Japan