1. Department of Thyroid and Breast Surgery, Liaocheng People's Hospital, Liaocheng, Shandong 252000, P.R. China
2. Department of General Surgery, Gaotang County People's Hospital, Liaocheng, Shandong 252800, P.R. China
3. Department of Thoracic Surgery, Liaocheng Tumor Hospital, Liaocheng, Shandong 252800, P.R. China