Hormone Therapy for Metastatic Breast Cancer
Watch Susan G. Komen®’s January 2025 MBC Impact Series, New Treatments and Approaches for Estrogen Receptor Positive Metastatic Breast Cancer.
What is hormone therapy?
Estrogen and progesterone are female hormones produced in the body. Some breast cancer cells have special proteins inside, called hormone receptors. When hormones attach to hormone receptors, the cancer cells with these receptors grow.
Hormone therapy drugs work by preventing hormone receptor-positive cancer cells from getting the estrogen they need to grow.
Hormone therapies may also be called endocrine therapies. The endocrine system in the body makes hormones.
Hormone therapy and metastatic breast cancer treatment
Hormone therapy is usually the first treatment for hormone receptor-positive metastatic breast cancers.
For women, the choice of hormone therapy depends on their menopausal status and any past hormone treatment for early breast cancer they had [4].
Men with hormone receptor-positive metastatic breast cancer most often take tamoxifen.
Learn about emerging areas in hormone therapy for metastatic breast cancer.
Learn more about treatment for metastatic breast cancer.
Hormone therapy for premenopausal women
For premenopausal women with hormone receptor-positive metastatic breast cancer, hormone therapy almost always begins with ovarian suppression and either an aromatase inhibitor, tamoxifen or other hormone therapy drug.
Ovarian suppression lowers hormone levels in the body so the tumor can’t get the estrogen it needs to grow. Most often, ovarian suppression uses drugs (such as goserelin or leuprolide) to stop the ovaries from producing hormones, but it may involve surgery to remove the ovaries (oophorectomy).
Combining ovarian suppression and a hormone therapy drug (such as an aromatase inhibitor or tamoxifen) improves survival over either treatment alone [5].
If breast cancer progressed during past treatment with a hormone therapy drug, the same hormone therapy drug may not be an option for current treatment.
Learn more about ovarian suppression.
Learn more about aromatase inhibitors.
Learn more about tamoxifen.
Hormone therapy for postmenopausal women
After menopause, hormone therapy for women with metastatic breast cancer can be an aromatase inhibitor, tamoxifen, fulvestrant or other hormone therapy drug.
If the first hormone therapy stops working and the cancer starts to grow again, a second hormone therapy can be used. If the second drug stops working, another can be tried.
Ovarian suppression isn’t helpful for postmenopausal women because their ovaries have already stopped producing large amounts of estrogen. (Postmenopausal women still make a small amount of estrogen in fat tissue and the adrenal glands.)
Learn more about aromatase inhibitors.
Learn more about tamoxifen.
Hormone therapy drugs for metastatic breast cancer
Some hormone therapy drugs are pills and some are given by injection under the skin (a shot).
Hormone therapies for metastatic breast cancer |
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Drug name |
Brand name |
Used in premenopausal or postmenopausal women? |
Injection or pill? |
Anastrozole |
Arimidex |
Postmenopausal |
Pill |
Elacestrant |
Orserdu |
Postmenopausal |
Pill |
Exemestane |
Aromasin |
Postmenopausal |
Pill |
Fulvestrant |
Faslodex |
Postmenopausal |
Injection |
Goserelin |
Zoladex |
Premenopausal |
Injection |
Imlunestrant |
Inluriyo |
Premenopausal and postmenopausal |
Pill |
Letrozole |
Femara |
Postmenopausal |
Pill |
Leuprolide |
Lupron |
Premenopausal |
Injection |
Megestrol acetate |
Megace |
Premenopausal and postmenopausal |
Pill |
Tamoxifen |
Nolvadex |
Premenopausal and postmenopausal |
Pill |
Toremifene |
Fareston |
Postmenopausal |
Pill |
To learn more about a specific hormone therapy, visit the National Institutes of Health’s Medline Plus website.
How do hormone therapies work?
Hormone therapy drugs slow or stop the growth of hormone receptor-positive breast cancers in a few ways:
- Hormone therapies, such as tamoxifen, attach to the hormone receptor in the cancer cell and block estrogen from attaching to the receptor.
- Hormone therapies, such as aromatase inhibitors and ovarian suppression, lower the level of estrogen in the body so the cancer cells can’t get the estrogen they need to grow.
- Hormone therapies, such as fulvestrant and elacestrant, degrade estrogen receptors. These drugs cause the estrogen receptor to be broken down by the cell.
Hormone therapy and ESR1 tumor gene mutations
Some breast cancers have an ESR1 gene mutation. This mutation is in the genes of the breast cancer cells, not the genes of the person.
All hormone receptor-positive, HER2-negative metastatic breast cancers are tested for ESR1 tumor gene mutations [4,6]. This can be done by testing tumor DNA in your blood or by testing tumor tissue.
ESR1 tumor gene mutations are uncommon when a person is first diagnosed with metastatic breast cancer. However, they become more common as people get hormone therapy and their cancers become resistant to treatment. So, it’s important to re-test for ESR1 tumor gene mutations.
Testing for ESR1 tumor gene mutations is done at the time of the diagnosis of metastatic breast cancer and each time the cancer progresses (spreads).
The hormone therapy drugs elacestrant (Orserdu) and imlunestrant (Inluriyo) may be used to treat hormone receptor-positive, HER2-negative metastatic breast cancers that have an ESR1 tumor gene mutation in women that have been treated with hormone therapy in the metastatic setting.
Learn more about elacestrant and imlunestrant.
| For a summary of research studies on elacestrant, imlunestrant and metastatic breast cancer treatment, visit the Breast Cancer Research Studies section. |
Drugs used in combination with hormone therapy
Some drugs are used in combination with hormone therapy. For hormone receptor-positive metastatic breast cancers that are also HER2-negative, one of these drugs may be included in the treatment plan.
Some of these drugs are only used to treat metastatic breast cancers that have a PIK3CA, AKT1 or PTEN tumor gene mutation. These mutations are in the genes of the breast cancer cells, not the genes of the person.
All hormone receptor-positive, HER2-negative metastatic breast cancers are tested for PIK3CA, AKT1 and PTEN tumor gene mutations [4,6]. This can be done by testing the tumor DNA in your blood or by testing tumor tissue.
Drugs used in combination with hormone therapy |
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Metastatic breast cancer is: |
Drug name (brand name) |
Class of drugs |
|
Abemaciclib (Verzenio) Palbociclib (Ibrance) Ribociclib (Kisqali) |
|
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Everolimus (Afinitor) |
|
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Alpelisib (Piqray) Inavolisib (Itovebi) |
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Capivasertib (Truqap) |
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Treatment guidelines for metastatic breast cancer
Although the exact treatment for metastatic breast cancer varies from person to person, guidelines help make sure high-quality care is given. These guidelines are based on the latest research and agreement among experts.
The National Comprehensive Cancer Network (NCCN) and the American Society of Clinical Oncology (ASCO) are respected organizations that regularly review and update their guidelines.
In addition, the National Cancer Institute (NCI) has treatment overviews.
Talk with your health care team about which treatment guidelines they follow.
Monitoring metastatic breast cancer
You’ll be monitored (checked) regularly with scans to see if the cancer is responding to treatment. If the treatment is no longer working, or you’re having a lot of side effects, your health care provider will change your treatment or discuss other options.
When hormone therapy stops working
At some point, even though it may be years away, hormone therapy almost always stops working. At this point, chemotherapy or other therapies may be recommended.
Learn more about how metastatic breast cancer is monitored.
Side effects of hormone therapies
Different hormone therapies have different side effects.
If you have ovarian suppression combined with tamoxifen or an aromatase inhibitor, you may have more side effects from the loss of estrogen than with the use of tamoxifen or an aromatase inhibitor alone.
Before you begin hormone therapy, talk with your health care team about possible side effects and how to manage them.
Learn about the side effects of tamoxifen.
Learn about the side effects of aromatase inhibitors.
Learn about the side effects of ovarian suppression.
Ashley Fernandez, living with metastatic breast cancer
“What keeps me going is my new normal. My life with cancer is completely different, I know I have it and I live with it every single day but it doesn’t take over every single day.”
Clinical trials
Clinical trials offer the chance to try new treatments and possibly benefit from them. They can also study other parts of care, such as ways to manage side effects. We encourage you to talk with your oncologist and consider joining a clinical trial if there’s one right for you.
Some clinical trials are available as the first step in treating metastatic breast cancer. Others are for later in the disease course.
Consider joining a clinical trial when you’re newly diagnosed, when your oncologist is considering changing treatments or when there are limited treatment options.
Read our blogs:
- Four Things to Know About Clinical Trials When You’re Diagnosed with Breast Cancer
- How Do You Thank Someone for Time
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Susan G. Komen® Patient Care Center |
If you or a loved one needs information or resources about clinical trials, the Patient Care Center can help. Contact the Komen Breast Care Helpline at 1-877-465-6636 or email clinicaltrialinfo@komen.org. Se habla español. |
Metastatic Trial Search |
The Metastatic Trial Search is an online clinical trial matching tool that can help you find clinical trials that fit your needs. You can also register to receive Trial Alerts. |
Learn more about clinical trials for people with metastatic breast cancer.
Learn what Komen is doing to help people find and participate in breast cancer clinical trials, including trials supported by Komen.
Learn how Komen-funded research is improving treatment for breast cancer.
Prescription drug assistance
The cost of drug therapies for metastatic breast cancer can quickly become a financial burden for you and your family.
Medicare and many insurance companies offer prescription drug plans. One may already be included in your policy, or you may be able to buy an extra plan for prescriptions.
Tamoxifen and aromatase inhibitors (anastrozole, exemestane and letrozole) all have generic forms. Generic drugs cost less than name brand drugs but are just as effective.
Many hospitals have financial counselors who can discuss insurance and cost coverage with you.
You may qualify for programs that help with drug costs or offer low-cost or free prescriptions. A financial counselor or social worker at your hospital can help you learn about these programs.
Learn more about insurance plans and prescription drug assistance programs.
Learn more about other financial assistance programs.
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Komen Financial Assistance Program |
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Susan G. Komen® created the Komen Financial Assistance Program to help those struggling with the costs of breast cancer treatment by providing financial assistance to eligible individuals. To learn more about this program and other helpful resources, call the Komen Patient Care Center at 1-877 GO KOMEN (1-877-465-6636) or email helpline@komen.org. Se habla español. Learn about other financial assistance programs. |
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Susan G. Komen®‘s position on fairness in oral cancer drug coverage |
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Insurance coverage of oral cancer drugs Cancer medications given through an IV into a vein or by an injection (under the skin or into a muscle) are usually covered under a health insurance plan’s medical benefit. However, oral cancer drugs (cancer medications that are pills) are usually covered under a health insurance plan’s prescription drug benefit. As a result, people often find themselves facing high out-of-pocket costs when filling prescriptions for oral cancer drugs. Sometimes these costs can be thousands of dollars a month. The impact of high cost-sharing High prescription drug costs and the resulting out-of-pocket burden on patients are a barrier to health care. They can prevent people from getting the medications prescribed by their health care providers. No one should be forced to get less appropriate treatment because an insurer gives more coverage for IV and injectable drugs than for pills. Efforts to increase fairness in drug coverage Komen supports state and federal efforts to require insurers to provide the same or better coverage for oral cancer drugs as they do for IV and injectable cancer drugs. This would help make sure patients have access to affordable, appropriate treatment. Become a Komen Advocacy Insider Sign up to be a Komen Advocacy Insider and get informed when action is needed on oral drug coverage parity at the state or national level. |
SUSAN G. KOMEN® METASTATIC BREAST CANCER SUPPORT RESOURCES |
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Updated 03/13/26
This content is regularly reviewed by an expert panel including researchers, practicing clinicians and patient advocates.
