Stratification according to Tumor Node Metastasis (TNM) stage revealed that only for Stages I and II there were significant differences in tumor-infiltrating CD8 + , CD8 + TCF1 + , TCF1 + cells along with CD8 + Ki67 / CD8 + and CD8 + TCF1 + / CD8 + ratios among breast cancer subtypes (Supplementary Tables 3–5). This evidence concerns the gene CD8A and breast cancer.