1. Department of Medical Oncology and Hematology, Kobe University Hospital, Kobe, Japan
2. Kobe University Hospital Cancer Center, Kobe, Japan
3. Japan Clinical Oncology Group Data Center/Operations Office, National Cancer Center Hospital, Tokyo, Japan
4. Department of Radiation Oncology, National Cancer Center Hospital East, Kashiwa, Japan
5. Department of Otolaryngology, National Hospital Organization Tokyo Medical Center, Tokyo, Japan
6. Department of Head and Neck Surgery, Aichi Cancer Center Hospital, Nagoya, Japan
7. Department of Head and Neck Surgery, Hyogo Cancer Center, Akashi, Japan
8. Department of Head and Neck Surgery, Shikoku Cancer Center, Matsuyama, Japan
9. Division of Head and Neck Surgery, Miyagi Cancer Center, Natori, Japan
10. Division of Clinical Oncology, Shizuoka Cancer Center, Shizuoka, Japan
11. Department of Head and Neck Surgery, National Cancer Center Hospital East, Kashiwa
12. Department of Head and Neck Medical Oncology, National Cancer Center Hospital East, Kashiwa, Japan