In the biology of brain tumors, and particularly in gliomas, the importance of microglia/macrophages, which represent up to 50% of the tumor mass [13], has been extensively investigated (revision in [14,15,16]) and has revealed evidence on the initial ability of these cells to interfere with tumor progression, which soon turn into a support for tumor invasion [17,18] and growth by the release of several soluble factors such as stress-inducible protein 1 (STI1), epidermal growth factor (EGF), interleukin 6 (IL-6), and transforming growth factor-β (TGF- β) [19,20,21]. Here, IL6 is linked to central nervous system cancer.