In addition to understanding the type of breast cancer and the stage, it’s critical that your oncologist has the cancer cells tested for hormone receptors and the HER2 protein. The results play a role in the type of breast cancer treatment that’s recommended.
Hormone receptor-positive breast cancer means that the cancer cells have a protein in or on them that attracts estrogen, progesterone, or both hormones. An overabundance of these hormones fuels the growth of the cancer cells. Not all breast cancers have these receptors.
Hormone Receptor Categories of Breast Cancer
- Estrogen-receptor positive (ER+): The breast cancer cells have receptors for the hormone estrogen. ER+ results suggest that the cancer cells may receive signals from estrogen that could promote their growth.
- Progesterone-receptor positive (PR+): The breast cancer cells have receptors for the hormone progesterone. PR+ results mean that the cancer cells may receive signals from progesterone that could promote their growth.
- HER2 positive: HER2 (human epidermal growth factor receptor 2) is a protein that appears on the surface of some breast cancer cells. A special test is done to determine whether this protein is present, indicating that the breast cancer could grow and spread quickly. About 1 in f 5 women test positive for HER2.
- Triple-negative: These breast cancer cells test negative for estrogen receptors, progesterone receptors, and HER2. Triple-negative breast cancer will be treated differently than the other types of breast cancer since hormones are not playing a role in the breast cancer’s growth.
Hormone Therapies and Targeted Therapies for Breast Cancer
Breast cancer treatments have been developed to specifically counteract ER+, PR+ and HER2 positive breast cancers.
For ER+ and PR+ a hormone therapy will most likely be included with other cancer treatments to block the receptors on the cancer cells from attracting the hormone. This slows the growth of the cancer.
The HER2 protein can also be blocked with a special category of drugs called targeted therapy. Clinical research has recently made available several targeted therapies for breast cancer patients that specifically block the growth of the HER2 protein, slowing the growth of the cancer.