The types of breast cancer can refer to a few different things. Doctors can classify breast cancer based on whether or not it is invasive (meaning it has spread to surrounding breast tissue), whether or not it begins in the milk ducts, whether or not it is carcinoma (meaning it begins in the lining of the tissues lining internal organs), and more.
Another way to categorize breast cancer is by receptor status. “There are different subtypes of breast cancer based on what receptors are expressed on the surface of the breast cancer cell. There are hormone receptors, estrogen and progesterone, and then there’s a protein called HER2,” says Amy Tiersten, MD, oncologist at Dubin Breast Center at Mount Sinai Hospital in New York City.
American Cancer Society. (2022). Breast cancer HER2 status.
American Cancer Society. (2021). Breast cancer hormone receptor status.