These studies confirm the paucity of CD8+ T cells and abundance of myeloid cells in ER+ cancers, with fewer NK cells, B cells, granulocytes, plasma cells, basophils, and plasmacytoid dendritic cells, and reveal the continuum of differentiation states, particularly of intratumoral T cells and myeloid-derived immune cell subpopulations. The gene discussed is CD8A; the disease is cancer.