1. Department of Otolaryngology and Head and Neck Surgery, University of Tokyo , Tokyo, Japan
2. Department of Otolaryngology-Head and Neck Surgery , Faculty of Medicine and Graduate School of Medicine, , Sapporo, Japan
3. Hokkaido University , Faculty of Medicine and Graduate School of Medicine, , Sapporo, Japan
4. Department of Medical Oncology and Hematology , Cancer Center, , Kobe, Japan
5. Kobe University Hospital , Cancer Center, , Kobe, Japan
6. Department of Head and Neck Medical Oncology, National Cancer Center Hospital East , Kashiwa, Japan
7. Department of Head and Neck Surgery, Aichi Cancer Center Hospital , Nagoya, Japan
8. Department of Head and Neck Surgery, Tokyo Medical and Dental University , Tokyo, Japan
9. Department of Head and Neck Surgery, National Cancer Center Hospital East , Kashiwa, Japan
10. Department of Otolaryngology-Head and Neck Surgery, Nara Medical University , Nara, Japan
11. Divisions of Gastrointestinal Oncology, Shizuoka Cancer Center , Kashiwa, Japan
12. Department of Otorhinolaryngology , Head and Neck Surgery, , Yokohama, Japan
13. Yokohama City University, School of Medicine , Head and Neck Surgery, , Yokohama, Japan
14. Department of Radiation Oncology, Aichi Cancer Center Hospital , Nagoya, Japan
15. Department of Radiation Oncology, National Cancer Center Hospital East , Kashiwa, Japan
16. Department of Radiation Oncology , Faculty of Medicine and Graduate School of Medicine, , Japan
17. Hokkaido University , Faculty of Medicine and Graduate School of Medicine, , Japan
18. Department of Medical Oncology, Cancer Institute Hospital , Tokyo, Japan
19. Department of Medical Oncology, Kindai University Faculty of Medicine , Higashi-Osaka, Japan
20. Division of Medical Oncology, Hyogo Cancer Center , Hyogo, Japan