The IR subtype showed high expression of numerous cytokine/chemokine signalling pathway components found in lymphoid cells, and over-expression of CD4 and CD8A. In both ER-negative and ER positive/HER2 positive breast cancer, the presence of CD8+ T cells was shown to be associated with a significant reduction in the relative risk of death from disease30. Here, ESR1 is linked to breast carcinoma.