Breast cancer types are broadly categorized as human epidermal growth factor receptor-2 (HER2)-overexpressing, estrogen receptor (ER)-positive, progesterone receptor (PR)-positive, or triple-negative breast cancer (TNBC), and of these, HER2-overexpressing and TNBC have the poorest prognoses. The gene discussed is PGR; the disease is triple-negative breast carcinoma.