ESR1 and triple-negative breast carcinoma: Despite being classified as a triple-negative breast cancer (TNBC) entity (lacking expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2)) and designated as a distinct basal-like tumour, ACCB is characterised by a low incidence of axillary involvement and distant metastasis [3].