What are estrogen receptor/progesterone receptor (ER/PR) tests?

Estrogen receptor/progesterone receptor (ER/PR) tests are used to help guide breast cancer treatment. Receptors are proteins that attach to certain substances. ER/PR tests look for receptors that attach to the hormones estrogen and progesterone in a sample of breast cancer tissue. Estrogen and progesterone play key roles in a woman’s sexual development and reproductive functions. Men also have these hormones, but in much smaller amounts.

About 70 percent of all breast cancers in women have receptors that attach to estrogen and/or progesterone. About 80 percent to 90 percent of breast cancers in men have these receptors. Breast cancers with estrogen and/or progesterone receptors include the following types:

• ER-positive (ER+): Cancers that have estrogen receptors (ER)
• PR-positive (PR+): Cancers that have progesterone receptors (PR)
• Hormone receptor-positive (HR+): Cancers that have one or both types of these receptors.

Breast cancers without ER or PR receptors are known as HR-negative (HR-).

ER/PR tests will show whether there are ER and/or PR receptors on your breast cancer cells. Test results are frequently referred to as the hormone receptor status. If your hormone receptor status shows you have one or both of these receptors on your cancer cells, you may respond well to certain types of treatments.

Other names: ER/PR IHC testing, hormone receptor status