1. Department of Head and Neck Surgery, Aichi Cancer Center Hospital, Aichi, Japan
2. Department of Head and Neck Surgery, Graduate School of Medicine, Tokyo Medical and Dental University, Tokyo, Japan
3. Department of Medical Oncology/Hematology and Cancer Center, Kobe University Hospital, Hyogo, Japan
4. Department of Otolaryngology––Head and Neck Surgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Hokkaido, Japan
5. Department of Head and Neck Surgery, National Cancer Center Hospital East, Chiba, Japan