1. Department of Radiation Oncology, Chang Gung Memorial Hospital, Chiayi, Taiwan
2. College of Medicine, Chang Gung University, Tao-yuan, Taiwan
3. Department of Otolaryngology—Head and Neck Surgery, Chang Gung Memorial Hospital, Chiayi, Taiwan
4. Health Information and Epidemiology Laboratory, Chang Gung Memorial Hospital, Chiayi, Taiwan
5. Graduate Institute of Clinical Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan