1. Department of Thyroid Surgery, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong Province, 264000, China
2. Department of Otolaryngology-Head and Neck Surgery, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong Province, 264000, China
3. Departments of Head and Neck Surgery, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, U.S.A.
4. Department of Epidemiology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, U.S.A.