IL6 and neoplasm: Increased serum levels of various cytokines were also observed in the circulation of castration-resistant PCs (CRPCs) patients, including FGF, EGF, IL-6, IL-10, GM-CSF, IGF, and TGF-β, sometimes along with their respective receptors: they have a role in promoting tumor progression and/or immune evasion [44,160].