1. Department of Head and Neck Medical Oncology National Cancer Center Hospital East, KashiwaJapan
2. Department of Medical Oncology and Hematology Kobe University Hospital KobeJapan
3. Japan Clinical Oncology Group Data Center National Cancer Center TokyoJapan
4. Japan Clinical Oncology Group Operations Office National Cancer Center TokyoJapan
5. Department of Head and Neck Surgery KashiwaJapan
6. Department of Radiation Oncology National Cancer Center Hospital EastKashiwaJapan
7. Department of Head and Neck Surgery Aichi Cancer Center NagoyaJapan
8. Department of Head and Neck Surgery Hyogo Cancer Center AkashiJapan
9. Department of Head and Neck Surgery Shikoku Cancer Center MatsuyamaJapan
10. Division of Head and Neck Surgery Miyagi Cancer Center NatoriJapan
11. Department of Clinical Oncology Jichi Medical University ShimotsukeJapan
12. Division of Clinical Oncology Shizuoka Cancer Center ShizuokaJapan
13. Department of Otolaryngology Hokkaido University Hospital SapporoJapan
14. Department of Head and Neck Surgery Kanagawa Cancer Center YokohamaJapan
15. Department of Otolaryngology National Hospital Organization Tokyo Medical CenterTokyo Japan