Statistical analysis
EVENT
All data were analyzed using SPSS 23.0 statistical software (SPSS, Inc., Chicago, IL, USA) and GraphPad Prism 5 software (GraphPad Software, Inc., La Jolla, CA, USA). Descriptive analysis was utilized to display clinicopathological features. The Kaplan–Meier method was used to estimate PFS and 95% confidence intervals (CIs) for the total population and the subgroups. Cox univariate and multivariate models were used to determine the predictive value of variables for PFS. In the analysis of progression-free survival, data from patients who did not have any documented event, were lost to follow-up or died from any cause were censored at the last date when the patient was known to be event-free. All reported 