IL6 and neoplasm: Immunomodulatory factors such as TGF-β and IL-6 secreted by CAFs inhibit the activity of effector T cells and promote the accumulation of immunosuppressive cells such as regulatory T cells and myeloid-derived suppressor cells.By altering the physical properties of the tumor microenvironment, such as increasing the density of the extracellular matrix, CAFs limit the penetration of drugs into tumor tissues and reduce the effects of chemotherapy drugs and the killing effect of radiotherapy on tumor cells.