PGR and breast carcinoma: Of all breast cancer patients, those with TNBC have the worst prognosis.[34–36] These tumors are generally aggressive and lack the expression of drug targets, such as estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor-2 (HER2).[34–36] TNBC is especially troubling in African American (AA) women.