The density of CD3d+ CD8a+ cells (hereafter CD8 T cells) varied 38-fold greater across the PCa cohort (~17 to ~653 cells/mm2; Fig. 1h) but was not significantly different in LGG (mean = 71 cells/mm2) and HGG PCa (mean = 135 cell/mm2); it was also ~2–5-fold lower than either pMMR (254 cells/mm2) or dMMR (589 cells/mm2) CRC. This evidence concerns the gene CD8A and posterior cortical atrophy.