Hormone receptor status is important when choosing breast cancer treatment options. Determining tumor status is the first priority after breast biopsy or breast cancer surgery (mastectomy or lumpectomy). Whether it's positive (meaning estrogen and / or progesterone stimulate cancer cell growth) or negative (meaning hormones don't promote growth) will have a big impact on the next steps you take.
Hormone receptors and receptor tests
All breast cancers are examined under a microscope for estrogen and progesterone receptor biomarkers. About 70% of breast cancers are hormone receptor positive.
Hormones and receptors go together like a lock and a key. Receptors are proteins found on the surface of breast cells, and when hormones bind to them, the receptors cause the cells to grow and divide. All cells in the breast have receptors, but many more are found in breast cancer cells that are considered positive.
The goal of treatment is to block the signal generated when hormones bind to receptors. This requires one of two things:
- Decrease in the amount of hormones in the body.
- Block the receptor so that the hormone cannot bind to it.
In most cases, breast cancer tends to be positive or negative for both estrogen and progesterone receptors. Occasionally, a person will test positive for estrogen but not progesterone. The treatment is the same anyway.
Indicators of hormone receptor status
Your report will show the percentage of cells that tested positive for hormone receptors. Zero percent means that no receptors are found and 100 percent means that all cells tested have receptors.
Why Your Hormonal Status Matters
Estrogen receptor (ER +) and / or progesterone receptor (PR +) positive breast cancer is "fueled" by hormones. They differ from HER2-positive breast tumors, wherein tumor growth is mediated by growth factors that bind to HER2 receptors on cancer cells. Breast cancer that does not have any of these receptors is called triple negative .
Some breast cancers are hormone and HER2 receptor positive, which means that estrogen, progesterone, and growth factors can stimulate cell growth. These cancers are often called triple positive breast cancers.
An ER + or PR + score means that hormones make the tumor grow and hormone-suppressive treatments are likely to work.
If the result is negative (ER- or PR-), your tumor is not related to hormones, and your results will need to be evaluated in conjunction with other tests, such as your HER2 status , to determine the most effective treatment.
If the only information you have been given is that your hormone tests are negative, it is helpful to ask your doctor for a number that indicates the actual result. Even if the number is small, the tumor can be effectively treated with hormone therapy.
If you have an ER + and / or PR + tumor, hormone therapy is generally recommended. However, the choice of medications depends on your menopausal status.
Before menopause, the ovaries produce the most estrogen. To prevent this estrogen from feeding your cancer cells, drugs called selective estrogen receptor modulators are used. These medications, such as tamoxifen , bind to the estrogen receptor so estrogen cannot reach it.
After menopause, the situation is different because there is much less estrogen in the body. The main source of estrogen in postmenopausal women is the conversion of androgens (male-type hormones) in your body to estrogen. This reaction is catalyzed by an enzyme known as aromatase. Medications called aromatase inhibitors can block this enzyme, so your body cannot make estrogen, which causes the tumor to starve.
Three aromatase inhibitors available:
Sometimes these drugs can be used in premenopausal women after ovarian suppression therapy. After the first dose of medications that interfere with estrogen production in the ovaries or, in some cases, after ovaries are removed, these women switch from tamoxifen to an aromatase inhibitor. This strategy gives some a greater survival advantage.
Bisphosphonates can also be used in conjunction with aromatase inhibitors for early stage ER + postmenopausal breast cancer. This reduces the risk of recurrence and especially the spread of breast cancer to the bones.
For early-stage estrogen receptor-positive breast cancer, hormone therapy can reduce the risk of recurrence by about half.
Sometimes other hormonal treatments can also be used. A drug called Faslodex (fulvestrant) is a selective estrogen receptor suppressant (SERD). It is sometimes used to treat women who develop cancer while taking tamoxifen or an aromatase inhibitor. Also, other hormonal treatments for metastatic breast cancer may be considered for some people.
In the past, treatment with tamoxifen or aromatase inhibitors generally lasted five years. However, studies have shown that for women at high risk of relapse, longer treatment may be beneficial. In light of this new research, it is important to speak with your doctor about current recommendations for the duration of treatment.