1. From the Departments of Radiation Oncology, Medical Oncology, Otolaryngology, Preventive Medicine and Biometrics, and Pathology, University of Colorado, Aurora, CO; Department of Radiation Oncology, Christiana Hospital Medical Center, Wilmington, DE; Department of Radiation Oncology, Beth Israel Medical Center, New York, NY; Department of Radiation Oncology, University of Pennsylvania Medical Center, Philadelphia, PA; and National Cancer Institute, Bethesda, MD