Know the Science: HR = Hormone receptor. HR+ means tumor cells have receptors for the hormones estrogen or progesterone, which can promote the growth of HR+ tumors. Hormone therapies like tamoxifen can be used to treat HR+ tumors. HER2 = Human epidermal growth Factor receptor, HER2+ means tumor cells overexpress (make high levels of) a protein, called HE2/neu, which has been shown to be associated with certain aggressive types of breast cancer. Trastuzumab and some other therapies can target cells that overexpress HER2. HR+/HER2, aka “LuminalA”. 73% of all breast cancer cases: best prognosis, most common subtype for every race, age, and poverty level. HR-/HER2, aka “Triple Negative”: 13% of all breast cancer cases, Worst prognosis, Non-Hispanic blacks have the highest rate of this subtype at every age and poverty level. HR+/HER2+, aka “Luminal B”, 10% of all breast cancer cases, little geographic variation by state. HR-/HER2+, aka”HER2-enriched”, 5% of all breast cancer cases, lowest rates for all races and ethnicities. Source: Special section of the Annual Report to the Nation on the Status of Cancer, 1975-2011.