1 1 Department of Thyroid & Breast Surgery, West China Hospital, Sichuan University, Chengdu 610041, China ; 2 Department of General Surgery, General Hospital of the People's Liberation Army (PLA), Beijing 100853, China ; 3 Department of Head and Neck Surgery, Cancer Institute & Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, National Cancer Center, Beijing 100021, China ; 4 Department of Gastrointestinal Surgery, People's Hospital of Peking University, Beijing 100044, China ; 5 Department of Thyroid Surgery, China-Japan Union Hospital of Jilin University, Changchun 130033, China ; 6 Department of General Surgery, Second Affiliated Hospital of Medical College of Zhejiang University, Hangzhou 310009, China ; 7 Department of Breast and Thyroid Surgery, Union Hospital Affiliated to Huazhong University of Science and Technology, Wuhan 430022, China ; 8 Department of Head and Neck Surgery, Sun Yat-sen University Cancer Center, Guangzhou 510060, China ; 9 Department of Thyroid Surgery, The First Affiliated Hospital of China Medical University, Shenyang 110001, China ; 10 Department of Thyroid Surgery, The First Affiliated Hospital of Kunming Medical University, Kunming 650032, China ; 11 Department of Surgery, The Second Affiliated Hospital of Guizhou Medical University, Kaili 556000, China ; 12 Department of General Surgery, Sixth People's Hospital Affiliated to Shanghai Jiao Tong University, Shanghai 200233, China ; 13 Department of Thyroid & Breast Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China ; 14 Department of Head and Neck Surgery, Affiliated Cancer Hospital of Zhengzhou University, Zhengzhou 450008, China ; 15 Department of Thyroid Surgery, Union Hospital Affiliated to Fujian Medical University, Fuzhou 350001, China.