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Hormone Receptor Status

Testing for hormone receptors is important because the results help you and your doctor decide whether the cancer is likely to respond to hormonal therapy medicines.

Your pathology report will include the results of a hormone receptor assay, a test that tells you whether or not the breast cancer cells have receptors for the hormones estrogen and progesterone. Hormone receptors are proteins — found in and on breast cells — that pick up signals from the hormones telling the cells to grow.

A breast cancer is estrogen receptor-positive if it has receptors for estrogen. This suggests that the cancer cells, like normal breast cells, may receive signals from estrogen that tell the cells to grow. The cancer is progesterone receptor-positive if it has progesterone receptors. Again, this means that the cancer cells may receive signals from progesterone that tell them to grow. Roughly two out of every three breast cancers test positive for hormone receptors.

Testing for hormone receptors is important because the results help you and your doctor
decide whether the cancer is likely to respond to hormonal therapy medicines.

It’s important to know that some hormone receptor-positive breast cancers can lose their receptors over time. The opposite is also true: hormone receptor-negative cancers can develop hormone receptors.

If breast cancer comes back after treatment, it's a good idea to ask your doctor about another biopsy to test the cancer for hormone receptors. If the cancer cells no longer have receptors, hormonal therapy is unlikely to help treat the cancer. If the cells have developed hormone receptors, hormonal therapy may offer benefits.


What hormone receptors do

Hormone receptors, like other cell receptors, are special proteins found in and on the surface of certain cells throughout the body, including breast cells. These receptor proteins are like the eyes and ears of the cells, receiving messages from hormones and other substances in the bloodstream and then telling the cells what to do. The receptors act like an on-off switch for an activity in the cell. If the right substance comes along that fits into the receptor — like a key fitting into a lock — the switch is turned on and that particular activity in the cell begins.


Understanding hormone receptor test results

Most labs use a special staining process that makes hormone receptors show up in a sample of breast cancer tissue. The test is called an immunohistochemical staining assay, or ImmunoHistoChemistry (IHC). Not all labs use the same method for analyzing the results of the test, and they don't report the results in exactly the same way. So you may see any of the following on your pathology report:

  • A percentage that tells you how many cells out of 100 stain positive for hormone receptors. You will see a number between 0% (none have receptors) and 100% (all have receptors).

  • An Allred score between 0 and 8. This scoring system is named for the doctor who developed it. The system looks at what percentage of cells test positive for hormone receptors, along with how well the receptors show up after staining, called intensity. This information is then combined to score the sample on a scale from 0 to 8. The higher the score, the more receptors were found and the easier they were to see in the sample.

  • The word positive or negative.

Keep in mind that the breast cancer should be tested for both estrogen receptors and progesterone receptors. If your result is reported as just positive or negative, ask your doctor for a more definite percentage, rating, or other number. You also can ask about how these more precise results might influence treatment decisions for your particular situation.

Different labs have different cutoff points for calling the cancer either hormone receptor-positive or hormone-receptor-negative. For example, if less than 10% of the cells — or fewer than 1 in 10 — stain positive, one lab might call this hormone receptor-negative breast cancer. Another lab might consider the cancer hormone receptor-positive, even though it is a low result. Research studies have shown that even cancers with low numbers of hormone receptors may respond to hormonal therapy.

A score of 0 generally means that hormonal therapy will not be helpful in treating the breast cancer. When the score is 0, the cancer is called hormone-receptor-negative.

Sometimes the lab report will say the hormone receptor status is unknown. If you receive an unknown result for hormone receptor status, ask your doctor what it means and what additional steps should be taken to determine the hormone receptor status of the cancer.

Most breast cancers are hormone receptor positive:

  • about 80% of breast cancers are estrogen receptor-positive, abbreviated as ER+

  • about 65% of breast cancers are both estrogen receptor-positive breast and progesterone receptor-positive, abbreviated as ER+/PR+

  • about 2% of breast cancers are estrogen receptor-negative and progesterone receptor-positive, abbreviated as ER-/PR+

  • about 25% of breast cancers have no hormone receptors, called hormone receptor-negative, abbreviated as HR-


Treatments for hormone receptor-positive breast cancer

Hormonal therapy

Hormonal therapy, also called anti-estrogen therapy, endocrine therapy, or hormone therapy, is used to treat all stages of hormone receptor-positive breast cancer.

Hormonal therapy medicines work in two ways:

  • by blocking estrogen production in the body

  • by blocking the effects of estrogen on breast cancer cells

Hormonal therapy is not a treatment option for hormone receptor-negative breast cancer.

There are three main types of hormonal therapy medicines used to treat breast cancer:

  • aromatase inhibitors

  • selective estrogen receptor modulators (SERMs)

  • estrogen receptor downregulators (ERDs)

Aromatase inhibitors work by blocking the enzyme aromatase, which turns the hormone
androgen into small amounts of estrogen in the body. Aromatase inhibitors can’t stop the ovaries from making estrogen, so these medicines are mainly used to treat post-menopausal women because their ovaries aren’t working anymore.

Selective estrogen receptor modulators (SERMs) block the effects of estrogen on breast cancer cells by sitting in the estrogen receptors. If a SERM is in the estrogen receptor, estrogen can’t attach to the cancer cell and the cell doesn’t receive estrogen’s signals to grow and multiply.

SERMs can be used to treat both pre- and post-menopausal women, as well as men.

Estrogen receptor downregulators (ERDs), much like SERMs, block the effects of estrogen on breast cancer cells by sitting in the estrogen receptors. ERDs also lower the number of estrogen receptors and change the shape of breast cell estrogen receptors so they don’t work as well.

Learn more at Hormonal Therapy.

CDK4/6 inhibitors

CDK4/6 inhibitors are a a type of targeted therapy used to treat certain types of hormone receptor-positive, HER2-negative breast cancer. Targeted therapies are medicines that target specific characteristics of cancer cells, such as a protein that allows the cancer cells to grow in a rapid or abnormal way. Targeted therapies are generally less likely than chemotherapy to harm normal, healthy cells. Some targeted therapies are antibodies that work like the antibodies made naturally by our immune systems. These types of targeted therapies
are sometimes called immune targeted therapies.

CDK4/6 inhibitors interfere with the way breast cancer cells divide and multiply. To do this, they target specific proteins known as the cyclin-dependent kinases 4 and 6, which is abbreviated as CDK4/6.

Learn more about CDK4/6 inhibitors.

— Last updated on July 27, 2022, 1:54 PM