Population-based incidence rates of breast cancers that are negative forestrogen receptor (ER), progesterone receptor, and human epidermal growthfactor receptor 2/neu (triple-negative breast cancer[TNBC]) are higher among African American (AA) compared with white American(WA) women, and TNBC prevalence is elevated among selected populations ofAfrican patients. Here, PGR is linked to triple-negative breast carcinoma.