ESR1 and breast neoplasm: Triple negative breast cancers (TNBC) represent a heterogeneous subtype of breast tumors that generally lack expression of estrogen receptor (ER), progesterone receptor (PR) and the human epidermal growth factor receptor 2.1 TNBCs are highly proliferative and have a high rate of recurrence compared to other breast cancer (BCa) subtypes.2 Currently, there are no specific targeted therapies for the management of TNBC, hence treatment is limited to radio- and chemotherapy.