About Breast Cancer
Breast cancer is the most common malignancy among women, with nearly 255,000 cases diagnosed annually in the USA.
Overall, the average risk for a woman to develop breast cancer in the United States is approximately 13% (or 1 in 8 women will eventually be diagnosed with breast cancer).
Fortunately, most (80-85%) clinical breast changes (e.g., fatty growths) in women are benign (noncancerous), and only 3%-6% are considered cancerous, especially in women younger than 40.
What is Breast Cancer?
Breast cancer is a malignancy that invades one or both breasts. Breast cancer occurs almost entirely in women, but men can develop breast cancer, too. Ductal (small canals that develop from the lobules and carry the milk to the nipple) cancer is the most common type of breast cancer. Additionally, breast cancers that develop in the lobules (glands that produce breast milk) are classified as lobular cancers.
The 3 major subtypes of breast cancer include:
Hormone Receptor-Positive Breast Cancer: Normal breast cells and some breast cancer cells have receptors that attach to the hormones, estrogen and progesterone, which are required for cellular growth. Estrogen Receptor-positive (ER-positive) breast cancers contain estrogen receptors and Progesterone Receptor-positive (PR-positive) breast cancers contain progesterone receptors. If the cancer cell has one or both receptors (ER+ and/or PR+), the breast cancer is classified as hormone-receptive positive.
HER2-Positive Breast Cancer is characterized by breast cancer cells that have a protein receptor called HER2 (human epidermal growth factor receptor 2). When the gene that controls the HER2 protein is not functioning properly, the breast cells grow rapidly and divide uncontrollably.
Triple-negative breast cancer is an aggressive type of invasive breast cancer in which the cancer cells don’t have estrogen or progesterone receptors (ER or PR) or manufacture the HER2 protein.