PDCD1 and neoplasm: RT has shown an immunomodulating effect, instigating a localized stimulation of the immune system by increasing antigen presentation (auto-vaccination) through immunogenic cell death (ICD) [36], reducing myeloid-derived suppressor cells (MDSCs) [37], modifying macrophage polarization [37], increasing PD-1 tumor expression and stimulating vascular modification [38], all of which have the potential to modify the tumor microenvironment [39,40].