1. Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan
2. Department of Medical Oncology and Hematology, Kobe University Hospital, Kobe, Japan
3. Department of Head and Neck Surgery, National Cancer Center Hospital East, Kashiwa, Japan
4. Department of Radiation Oncology, Hokkaido University Hospital, Sapporo, Japan
5. Department of Otolaryngology, Head and Neck Surgery, University of Tokyo, Tokyo, Japan
6. Department of Otolaryngology – Head & Neck Surgery, Faculty of Medicine and Graduate School of Medicine, Sapporo, Japan