PGR and triple-negative breast carcinoma: Compared to women of European descent, AA women [4,6,7,8,9,10,11,12,13] and women of African descent world-wide [9,14,15,16] have a higher incidence of triple-negative breast cancer (TNBC) [17,18,19,20,21], which is characterized by the absence of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2).