1. Division of Gastroenterological Surgery, Department of General Surgical Science, Graduate School of Medicine Gunma University Maebashi Japan
2. Department of Head and Neck Surgery Osaka International Cancer Institute Osaka Japan
3. Department of Digestive Surgery Osaka International Cancer Institute Osaka Japan
4. Department of Otolaryngology‐Head and Neck Surgery, Graduate School of Medicine Kumamoto University Kumamoto Japan
5. Department of Gastroenterological Surgery, Graduate School of Medical Science Kumamoto University Kumamoto Japan
6. Department of Otolaryngology‐Head and Neck Surgery Tohoku University Graduate School of Medicine Sendai Japan
7. Department of Gastroenterological Surgery Tohoku University Graduate School of Medicine Sendai Japan
8. Advanced Trauma, Emergency and Critical Care Center/Gastroenterological and Pediatric Surgery Oita University Hospital Yufu Japan
9. Department of General Surgical Science Gunma University Graduate School of Medicine Maebashi Japan
10. National Hospital Organization Kyushu Cancer Center Fukuoka Japan
11. Department of Otolaryngology‐ Head and Neck Surgery National Defense Medical College Saitama Japan