Hormone Receptor Status

Normal breast tissue is very sensitive to the role of hormones, such as estrogen and progesterone.  These female hormones influence a woman's menstrual cycle, sexual development, pregnancy and childbirth.  While the levels of these hormones drop with menopause, smaller amounts remain in a woman's body.  Normal breast cells have receptors that respond to signals coming from these hormones while they circulate in the bloodstream.

Most breast cancer cells also have hormone receptors.  Knowing whether your breast cancer cells have hormone receptors is important in making treatment decisions.  Breast cancer cells that have estrogen receptors are said to be estrogen receptor positive (ER+), while those with progesterone receptors are progesterone receptor positive (PR+).  If your cancer is hormone receptor positive, it will likely respond to hormonal therapies – treatments that block the hormone receptors.  If your tumor is hormone receptor negative, hormonal therapies will not be effective, and your treatment plan will likely rely more on chemotherapy.

In recent years, researchers have learned that breast cancer exists in many forms and that hormonal status is not an all-or-nothing condition.  Individual breast cancers can include a high percentage of cells that have hormone receptors to those that have a very low percentage – or none.  Hormone receptor status can also change with the development of new cancers, with some tumors losing receptors and others gaining them.

Next: Triple Negative Breast Cancer.