PGR and breast cancer: Numerous population-based studies have found that, compared to White women with breast cancer, Black women are approximately twice as likely to be diagnosed with estrogen receptor negative (ER-), estrogen and progesterone receptor negative (ER-/PR-), or triple negative tumors (ER-, PR- and human epidermal growth factor receptor, HER2 negative), subtypes of the disease [10]–[17].