CD8A and breast cancer: In the immune regions at baseline (Fig. 2D) and after 2 weeks of ET (Fig. 2E), the most abundant immune cell-surface marker was the CD8 T-cell marker, followed by the CD68 macrophage marker, which is consistent with previous studies showing that the most abundant immune cells in breast cancer, including ER+ breast cancer, are T cells and myeloid cells (50).