1. Department of Surgery Tohoku University Graduate School of Medicine Sendai Japan
2. Department of Surgery Iwaki City Medical Center Iwaki Japan
3. Department of Hepato‐Biliary‐Pancreatic Surgery Osaka City University Graduate School of Medicine Osaka Japan
4. Department of Gastroenterology School of Medicine Bantane Hospital Fujita Health University Nagoya Japan
5. Second Department of Surgery Wakayama Medical University Wakayama Japan
6. Department of Surgery Institute of Gastroenterology Tokyo Women's Medical University Tokyo Japan