1. Department of Clinical Oncology, Shaanxi Provincial People's Hospital, Xi'an, Shaanxi 710068, P.R. China
2. Department of Oncology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
3. Department of Oncology, The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, P.R. China