1. Department of Otolaryngology/Head and Neck Surgery University of North Carolina School of Medicine Chapel Hill North Carolina U.S.A.
2. Department of Otolaryngology/Head and Neck Surgery University of Kansas Medical Center Kansas City Missouri U.S.A.
3. Department of Hematology/Oncology University of North Carolina School of Medicine Chapel Hill North Carolina U.S.A.
4. Department of Epidemiology University of North Carolina at Chapel Hill Chapel Hill North Carolina U.S.A.