While low doses of IR have anti-inflammatory effects (77), higher doses (>1 Gy) applied in tumor therapy are capable of stimulating the immune system in several ways: RT can enhance the expression of MHC-I on the surface of tumor cells alongside with cell death receptors Fas/CD95 and NKG2D ligand, thus boosting the recognition and killing of irradiated tumor cells through T cells and NK cells (78–80). Here, FAS is linked to neoplasm.