1. Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
2. Department of Neurosurgery, Chongqing Qianjiang Central Hospital, Chongqing 409000, P.R. China
3. Department of General Surgery, Chongqing Qianjiang Central Hospital, Chongqing 409000, P.R. China
4. Department of Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA