1. Department of Cardiac Surgery, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
2. Department of Otorhinolaryngology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China
3. Department of Oncology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266003, P.R. China