To determine if the percentage of PBMCs displaying p-STAT-3 correlated with the degree of immune suppression as measured by the fraction of Tregs in the CD4+ compartment in glioma patients, we measured the percentage of FoxP3-positive Tregs in the CD4+ lymphocyte population in a subset of GBM patients and compared the measurement to the same patient's percentage of p-STAT-3 positive PBMCs. Here, STAT3 is linked to central nervous system cancer.