1. Department of Otorhinolaryngology—Head and Neck Surgery and Cancer Research Institute, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Otorhinolaryngology—Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea.
3. Department of Pathology, Seoul National University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
5. Department of Internal Medicine, Kangwon National University Hospital, Chuncheon, Korea.