Metastatic breast cancer (also called stage IV or advanced breast cancer) is not a specific type of breast cancer. It is the most advanced stage of breast cancer.
Metastatic breast cancer is breast cancer that has spread beyond the breast and nearby lymph nodes to other organs in the body (most often the bones, lungs, liver or brain).
Although metastatic breast cancer has spread to another part of the body, it’s still breast cancer and treated as breast cancer.
For example, breast cancer that has spread to the bones is still breast cancer (not bone cancer). So, it's treated with breast cancer drugs, rather than treatments for cancer that began in the bones.
It’s estimated that more than 154,000 people in the U.S. have metastatic breast cancer .
Some women have metastatic breast cancer when first diagnosed with breast cancer (about 6 percent of diagnoses in the U.S.) . This is called de novo metastatic breast cancer.
Most often, metastatic breast cancer arises years after a person has completed treatment for early or locally advanced breast cancer. This is sometimes called a distant recurrence.
It's not your fault you have metastatic breast cancer. You did nothing to cause it.
The risk of metastasis after breast cancer treatment varies from person to person. It depends greatly on:
As hard as it is to hear, metastatic breast cancer cannot be cured today.
Unlike breast cancer that remains in the breast or nearby lymph nodes, you can't get rid of all the cancer that has spread to other organs.
This doesn’t mean metastatic breast cancer can’t be treated though. Treatment focuses on length and quality of life.
Your treatment plan is guided by many factors, including:
If the cancer is hormone receptor-positive, the first treatment is hormone therapy.
If the cancer is HER2-positive, anti-HER2 targeted therapy drugs such as trastuzumab (Herceptin) may be given.
For triple negative breast cancers that are PD-L1-positive, the first treatment may be the immunotherapy drug atezolizumab (Tecentriq) in combination with the chemotherapy drug paclitaxel.
Chemotherapy and radiation therapy can be used to shrink or slow the growth of tumors or to ease symptoms of the cancer itself. However, these therapies have side effects that can affect quality of life.
It's always OK to get a second opinion at any time during your treatment.
Learn more about factors that affect treatment options.
Learn about emerging areas in treatment.
Talking about quality of life issues with your health care providers and your family can help you decide what treatments are best for you.
Joining a support group may also help you think through these issues.
Learn about managing side effects and supportive care.
Learn about pain management.
Although the exact treatment for metastatic breast cancer varies from person to person, guidelines help ensure high-quality care. 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 providers about which treatment guidelines they use. Since there’s often a lag time between the latest research and guideline updates, most providers prefer to base their treatment on the latest research.
Modern treatments continue to improve survival for most people diagnosed with metastatic breast cancer. However, survival varies greatly from person to person.
Of the women who have metastatic breast cancer in the U.S. today, it’s estimated that 34 percent have lived at least 5 years beyond their diagnosis . Some women may live 10 or more years beyond diagnosis .
Tumors often become resistant (stop responding) to drugs used to treat metastatic breast cancer.
If you have metastatic breast cancer, you’ll be monitored every few months to see if the cancer is responding to treatment. This is called “restaging.” Tests may include a physical exam, blood tests and imaging tests (such as an X-ray, CT scan, PET scan or bone scan).
Some metastatic breast cancer cells need specific proteins or cell pathways to grow. Drugs that target the proteins or pathways can slow or stop the growth of these cancer cells for a period of time.
You can think of the proteins as traffic signs and the pathways as roads. Breast cancer cells must pass through the signs to continue along the road.
If the cancer cell hits a roadblock (such as a drug that targets the protein), it can't continue down that pathway.
At some point however, the cancer cell finds a detour around the roadblock and uses another pathway to continue to grow.
It’s normal to feel anxious before these tests (some call this “scan anxiety”). Talk with your health care provider about ways to cope with this stress.
Because metastatic breast cancers often develop resistance to drugs, it’s common to change therapies multiple times.
You usually start a drug therapy and see whether:
If the treatment is working (and the side effects aren't too bad) at the time of restaging, the treatment is typically continued.
If the treatment is no longer working or if you're having a lot of side effects, your oncologist may switch you to a different drug.
In some cases, blood tests for tumor markers may be used to help monitor metastatic breast cancer.
For example, you may be tested every few months for cancer antigen 15-3 (CA15-3) or cancer antigen 27.29 (CA27.29) . These tests are similar. Health care providers usually check one, but not both of these tests.
There is no test score that means the tumor has spread (the cancer has gotten worse).
Rather, whether your own test score rises or falls over time may give some information on tumor response to a drug or tumor spread.
Tumor marker tests are not helpful in every case. Some people with rising tumor marker levels don’t have tumor growth and some people with tumor growth have normal or unchanged tumor marker levels.
Providers don’t make treatment decisions based on serum tumor marker testing alone.
They may combine findings from a tumor marker test with information on symptoms and findings from imaging tests (such as bone scans). This combined information can help your providers understand if treatments are helping control tumor growth.
Talk with your provider about whether tumor marker testing is right for you.
Hormone therapy is usually the first treatment for hormone receptor-positive metastatic breast cancers.
Hormone therapy drugs work by preventing the cancer cells from getting the estrogen they need to grow.
For women, the choice of hormone therapy depends on menopausal status and any past hormone treatment for early breast cancer .
Some hormone therapy drugs (like tamoxifen and aromatase inhibitors) are pills. Others (like goserelin or fulvestrant) are given by injection (a shot).
Find a list of hormone therapy drugs used to treat metastatic breast cancer and whether they are pills or given by injection.
For premenopausal women with metastatic breast cancer, hormone therapy almost always begins with ovarian suppression.
Ovarian suppression lowers hormone levels in the body so the tumor can’t get the estrogen it needs to grow. This may involve surgery to remove the ovaries (oophorectomy) or, more often, drugs (such as goserelin or leuprolide) to stop the ovaries from producing hormones.
Tamoxifen is also used to treat metastatic breast cancer in premenopausal women. However, it may not be an option for women whose cancer progressed during past tamoxifen treatment.
Combining ovarian suppression and tamoxifen improves survival over either treatment alone .
After menopause, hormone therapy for women with metastatic breast cancer can be an aromatase inhibitor, tamoxifen or another anti-estrogen drug (such as fulvestrant).
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.
At some point, even though it may be years away, hormone therapy almost always stops working. At this point, chemotherapy may be recommended.
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.)
CDK4 and CDK6 are enzymes important in cell division. CDK4/6 inhibitors are a class of drugs designed to interrupt the growth of cancer cells.
The CDK4/6 inhibitors FDA-approved for breast cancer treatment are:
These 3 drugs are pills. Although they have not been compared directly to one another, studies show similar results with each drug [6-12].
Adding a CDK4/6 inhibitor to hormone therapy can give people with hormone receptor-positive, HER2-negative metastatic breast cancers more time before the cancer spreads compared to treatment without hormone therapy alone [6-12].
The CDK4/6 inhibitor abemaciclib may also be used alone to treat hormone receptor-positive, HER2-negative cancers that have progressed during past hormone therapy and chemotherapy.
The table below lists some possible side effects for CDK4/6 inhibitors.
Adapted from select sources [6-15].
Other CDK4/6 inhibitors are under study for use in metastatic breast cancer treatment.
For a summary of research studies on the use of CDK4/6 inhibitors in treating metastatic breast cancer, visit the Breast Cancer Research Studies section.
mTOR (mammalian target of rapamycin) inhibitors are a class of targeted therapy drugs that may increase the benefit of hormone therapy.
The mTOR inhibitor everolimus (Afinitor) is FDA-approved for the treatment of hormone receptor-positive, HER2-negative metastatic breast cancers in postmenopausal women.
Studies have shown the combination of everolimus and the aromatase inhibitor exemestane can slow the growth of such cancers better than exemestane alone [5,16-17].
Everolimus is a pill.
Some possible side effects of everolimus include mouth ulcers, infections, rash, fatigue, diarrhea, decreased appetite and in rare cases, lung problems [16-17].
Chemotherapy is a first treatment for metastatic breast cancers that are:
One benefit of chemotherapy is response time. Chemotherapy may shrink tumors faster than hormone therapy.
As with hormone therapies, if the first chemotherapy drug (or combination of drugs) stops working and the cancer begins to grow again, a second or third drug can be used.
The use of each type of chemotherapy drug (or combination of drugs) for metastatic breast cancer is called a “line” of treatment. For example, the first chemotherapy used is called the “first-line” treatment and the second is called the “second-line” treatment.
With each line of treatment, it becomes less likely the cancer will shrink. And, if the cancer does shrink, it’s often for a shorter period of time with each new drug.
It’s not uncommon for people to get multiple lines of chemotherapy regimens (often 4 or more) over the course of their treatment for metastatic breast cancer.
Learn more about chemotherapy.
Find a list of chemotherapy drugs commonly used to treat metastatic breast cancer.
About 10-20 percent of breast cancers have high amounts of a protein called HER2 on the surface of the cancer cells (called HER2-positive breast cancer) [18-19]. The HER2 protein is important for cancer cell growth.
A pathologist determines HER2 status by testing tumor tissue removed during a biopsy.
Anti-HER2 drugs are targeted therapies used to treat HER2-positive breast cancers
Trastuzumab (Herceptin) is a specially made antibody that targets HER2-positive cancer cells. When attached to the HER2 protein, trastuzumab can slow or stop the growth of these cells.
Trastuzumab is only used to treat HER2-positive breast cancers.
It can shrink tumors and slow the growth of HER2-positive metastatic breast cancers when used alone or combined with chemotherapy [20-22].
Trastuzumab is given by vein (through an IV) or by injection.
Trastuzumab has fewer (and different) side effects than chemotherapy. Although trastuzumab can cause headache, fever and chills, it doesn’t cause hair loss, nausea or vomiting, and has no effect on bone marrow.
In rare cases, deaths due to heart problems have been linked to the use of trastuzumab [4,20]. Although the chance of such an event is small, discuss this risk with your health care provider before starting treatment.
Your heart will be checked before and during treatment to help ensure there are no problems.
For a summary of research studies on trastuzumab and treatment of metastatic breast cancer, visit the Breast Cancer Research Studies section.
Some drugs are made from biological products (biologics) such as antibodies or proteins. Trastuzumab and pertuzumab (Perjeta) are breast cancer treatment drugs made from biologics (they are made from antibodies).
A biosimilar drug is a “generic like” version of a drug that contains biologics. Usually, the biosimilar protein has the exact same structure as the original biologic.
The name of a biosimilar drug includes the name of the original biologic drug. For example, trastuzumab-dkst is a biosimilar form of the drug trastuzumab.
A biosimilar drug may cost less than the original drug.
To be approved by the U.S. Food and Drug Administration (FDA), the biosimilar drug must work the same way as the original drug and it must have the same :
The side effects of the biosimilar drug cannot be different from those of the original drug. Also, the biosimilar drug must be the same form as the original drug. For example, if the original drug is given by vein (through an IV) the biosimilar drug must also be given by vein.
At this time, there are 4 FDA-approved biosimilar drugs for breast cancer treatment. They are all biosimilar forms of trastuzumab and can be used to treat early and metastatic HER2-positive breast cancers:
Other biosimilar drugs for breast cancer are under study.
Some drugs used to treat side effects of chemotherapy and other breast cancer treatments have biosimilar forms.
For example, some people get a white blood cell growth factor drug, such as filgrastim (Neupogen) or pegfilgrastim (Neulasta), to help maintain their blood counts during chemotherapy. Tbo-filgrastim (Granix) and pegfilgrastim-jmdb (Fulphila) are the biosimilar forms of these drugs.
Pertuzumab (Perjeta) is a specially made antibody that targets HER2-positive cancer cells, but in a different way than trastuzumab.
Pertuzumab is FDA-approved as a first treatment of HER2-positive metastatic breast cancers.
Study findings have shown pertuzumab in combination with trastuzumab and chemotherapy can slow the growth of HER2-positive metastatic breast cancer and increase survival better than trastuzumab and chemotherapy alone [24-25].
Pertuzumab is given by vein (through an IV).
Some possible side effects of pertuzumab include diarrhea, rash, vomiting, headache and dry skin [24-25].
For a summary of research studies on pertuzumab and treatment of metastatic breast cancer, visit the Breast Cancer Research Studies section.
Trastuzumab emtansine (T-DM1, Kadcyla) is a type of targeted therapy for HER2-positive metastatic breast cancer.
T-DM1 consists of trastuzumab linked to a chemotherapy called DM1. Combining these together allows the targeted delivery of chemotherapy to HER2-positive cancer cells.
T-DM1 is FDA-approved for the treatment of HER2-positive metastatic breast cancers that have progressed on trastuzumab and a taxane-based chemotherapy.
Study findings have shown T-DM1 can increase overall survival better than lapatinib plus the chemotherapy drug capecitabine for women with metastatic HER2-positive breast cancers .
T-DM1 is given by vein (through an IV).
Some possible side effects of T-DM1 include nausea, fatigue, muscle and joint pain, low platelet counts, headache and constipation . It can also cause liver and heart problems.
T-DM1 does not usually cause hair loss .
Tyrosine-kinase inhibitors, such as lapatinib (Tykerb), are a class of drugs that target enzymes important for cell functions (called tyrosine-kinase enzymes).
These drugs can block tyrosine-kinase enzymes at many points along the cancer growth pathway.
Lapatinib is FDA-approved for the treatment of HER2-positive metastatic breast cancer in women who have already had chemotherapy and trastuzumab.
Lapatinib is a pill.
Compared to chemotherapy alone, chemotherapy combined with lapatinib may give women with HER2-positive metastatic breast cancer more time before the cancer spreads [28-29].
Compared to use of the aromatase inhibitor letrozole alone, letrozole combined with lapatinib may give women with HER2-positive metastatic breast cancer more time before the cancer spreads [30-31].
Compared to use of trastuzumab alone, trastuzmab combined with lapatinib may give women with HER2-positive metastatic breast cancer more time before the cancer spreads .
Many therapies cannot pass through the blood to the brain (called the blood-brain barrier) to treat breast cancer that has spread to the brain.
Lapatinib is able to pass through the blood-brain barrier and early findings show it holds promise for HER2-positive metastatic cancer with brain metastases [33-36]. In rare cases, it can help shrink or slow the growth of brain metastases [32-35].
Some possible side effects of lapatinib include diarrhea, nausea, vomiting, rash and fatigue [28-30,34].
In rare cases, it’s been linked to liver and lung problems [28-30,34].
For a summary of research studies on the use of lapatinib in treating metastatic breast cancer, visit the Breast Cancer Research Studies section.
Poly(ADP-ribose) polymerase (PARP) is an enzyme involved in DNA repair. Some chemotherapy drugs damage tumor DNA. PARP inhibitors work to stop PARP from repairing tumor DNA to help the chemotherapy kill the cancer cells.
PARP inhibitors are only used in breast cancer treatment for people who have a BRCA1 or BRCA2 gene mutation. BRCA1/2-related breast cancers seem to be sensitive to DNA damage involving the PARP enzyme.
PARP inhibitors are not used to treat people who do not have BRCA1/2 gene mutation.
People with HER2-negative metastatic breast cancer who may get chemotherapy are encouraged to get BRCA1/2 genetic testing to see if a PARP inhibitor may be used for treatment .
Although PARP inhibitors have side effects, they are often easier to tolerate than chemotherapy drugs.
The PARP inhibitors olaparib (Lynparza) and talazoparib (Talzenna) are FDA-approved for breast cancer treatment.
The PARP inhibitor olaparib is used to treat HER2-negative metastatic breast cancer in people who have a BRCA1/2 gene mutation and have been treated with chemotherapy in the past (including chemotherapy for early breast cancer).
If the metastatic breast cancer is hormone receptor-positive, people should have also been treated with hormone therapy in the metastatic setting.
Compared to chemotherapy alone, olaparib may give women with a BRCA1/2 gene mutation who have HER2-negative metastatic breast cancer more time before the cancer spreads .
Olaparib is a pill.
Some possible side effects of olaparib include low red blood cell counts (anemia), nausea, vomiting, fatigue and low white blood cell counts . In rare cases, it can cause acute myeloid leukemia .
The PARP inhibitor talazoparib is FDA-approved for the treatment of HER2-negative metastatic breast cancer in people who have a known or suspected BRCA1/2 gene mutation and have been treated with chemotherapy in the past (including chemotherapy for early breast cancer).
Compared to chemotherapy alone, talazoparib may give women with a BRCA1/2 gene mutation who have HER2-negative metastatic breast cancer more time before the cancer spreads .
Talazoparib is a pill.
Some possible side effects of talazoparib include fatigue, low red blood cell counts (anemia), nausea and vomiting, headache and diarrhea . In rare cases, it can cause acute myeloid leukemia .
Drugs that help the body’s immune system attack cancer cells are now used to treat many cancers (including melanoma, lung cancer, bladder cancer and kidney cancer). Overall, immunotherapy drugs (including vaccines) are not as promising for breast cancer compared to other cancers at this time. However, some breast cancers may benefit from them.
Researchers are studying how to identify the best biomarkers for immunotherapy.
“Checkpoint inhibitors” are one type of immunotherapy drug. These drugs “take the brakes off” the natural factors that limit how the immune system can control tumor cells.
PD-L1-positve breast cancers express (have a lot of) programmed cell death protein 1 (PD-L1). Metastatic triple negative breast cancers should be tested for PD-L1 status.
The checkpoint inhibitor immunotherapy drug atezolizumab (Tecentriq) in combination with the chemotherapy drug paclitaxel is FDA-approved as a first treatment for PD-L1-positve metastatic triple negative breast cancer .
Compared to chemotherapy alone, atezolizumab in combination with paclitaxel may give women with PD-L1-positve metastatic triple negative breast cancer more time before the cancer spreads .
Whether atezolizumab is effective for the treatment of metastatic triple negative breast cancers that do not express (have little or no) PD-L1 is under study .
Other immunotherapy drugs are also under study.
Atezolizumab increases the risk of diabetes, thyroid problems, lung inflammation and colitis (inflammation of the intestines) .
Some possible side effects of atezolizumab plus paclitaxel include hair loss, pain or numbness in the hands or feet, fatigue, nausea, diarrhea, anemia, constipation, cough, headache and vomiting .
Learn more about talking with your health care provider.
It may be helpful to download and print our Questions to Ask Your Doctor card on metastatic breast cancer and take it with you to your next doctor appointment. There's plenty of space to write down the answers to these questions, which you can refer to later.
You can also download other Questions to Ask Your Doctor cards on many different breast cancer topics. These cards are a nice tool for people recently diagnosed with metastatic breast cancer, who may be too overwhelmed to know where to begin to gather information.
If you have metastatic breast cancer, talk with your health care provider before getting a seasonal flu shot to make sure it's safe for you. If you are a caregiver, the Centers for Disease Control and Prevention (CDC) recommends you get the seasonal flu shot.
Find more information from the CDC about the seasonal flu.
*Please note, the information provided within Komen Perspectives articles is only current as of the date of posting. Therefore, some information may be out of date at this time.
Facts for Life: Metastatic Breast Cancer
Research Fast Facts: Metastatic Breast Cancer
Breast Cancer 101 - Treatment for Stage IV
Questions to Ask Your Doctor About Metastatic Breast Cancer
Metastatic Breast Cancer
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