1. 1Division of Head and Neck Surgery, Department of Otolaryngology-Head and Neck Surgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
2. 2Department of Otolaryngology-Head and Neck Surgery, McGill University, Montreal, Quebec, Canada.
3. 3Centre for Clinical Epidemiology, Lady Davis Institute of the Jewish General Hospital, Montreal, Quebec, Canada.
4. 4Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins Hospital, Baltimore, Maryland.
5. 5VA Pittsburgh Health System, Pittsburgh, Pennsylvania.
6. 6UPMC Hillman Cancer Center, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
7. 7Division of Hematology and Oncology, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
8. 8Department of Otolaryngology-Head and Neck Surgery, Oregon Health & Science University, Portland, Oregon.
9. 9Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, California.