Statistical Analysis

Differences between the groups were analyzed using the Kruskal-Wallis H test (Graphpad Prim 5.0). Spearman’s correlation was performed to evaluate the interdependency of CSF cytokines and clinical features (SPSS 18.0). The ability of each CSF cytokine level to identify PCNSL was assessed with receiver-operator characteristic (ROC) curves, which included the sensitivity, specificity, cut-off value, area under the curve (AUC), 95% confidence interval (CI), and then was evaluated by K-fold cross-validation using R 3.2.2 pROC package. The predictive value of the CSF cytokine concentrations in the progression free survival (PFS) of patients with PCNSL was assessed with a log rank test (Graphpad Prim 5.0). The PFS was calculated from the date of CSF sample collection to the date of death and date of progression/recurrence or the date of the last follow-up. All tests were 2 tailed, and p < 0.05 was considered statistically significant.