1. School of Medicine University of California San Francisco San Francisco California U.S.A.
2. Department of Otolaryngology‐Head and Neck Surgery University of California San Francisco San Francisco California U.S.A.
3. Department of Radiation Oncology University of California San Francisco San Francisco California U.S.A.
4. Department of Epidemiology and Biostatistics University of California San Francisco San Francisco California U.S.A.