Notably, a recent retrospective analysis (n = 563) of the multicenter IKA trial that randomized stage 1–3 ER-positive BC patients to receive tamoxifen or no adjuvant therapy showed that CD8-positive sTILs were significantly higher in patients with PIK3CA-mutated tumors (OR: 1.65; 95% CI: 1.03–2.68)88. This evidence concerns the gene CD8A and breast cancer.