CD6 and Immunodeficiency: Six genes related to (a) immune checkpoints (n = 2; BTLA and CD6); (b) regulatory macrophages and T cells (n = 2; CCR7 and CD3D); and (c) immune deficiencies and unfavorable prognosis (n = 2; CD3E and FCGR2B) were down-regulated post-RT compared with pre-RT (statistical p-range: <0.0001–0.0415; Figure 1).