Treatment for metastatic breast cancer varies from person to person. Treatment is guided by:
- Characteristics of the cancer cells
- Where the cancer has spread
- Your symptoms
- Past breast cancer treatments
Learn more about factors that affect treatment options.
Tumors often develop resistance to drugs used to treat metastatic breast cancer. Therefore, it is common to change therapies fairly often.
Hormone therapy
Hormone therapy is usually the first treatment for metastatic cancers that are hormone receptor-positive. These drugs work by preventing the cancer cells from getting the estrogen they need to grow.
Some hormone therapies, like tamoxifen, attach to the estrogen receptors on the cancer cells and block estrogen from attaching to the receptor. Other therapies, like aromatase inhibitors, lower the level of estrogen in the body so that the cancer cells cannot get the estrogen they need.
For a woman, the choice of hormone therapy depends on menopausal status and any past hormone treatment for early breast cancer [52,66].
Learn more about hormone therapies.
Find a list of hormone therapies used to treat metastatic breast cancer.
Hormone therapy for premenopausal women
For premenopausal women, hormone therapy often begins with ovarian suppression. Ovarian suppression lowers hormone levels in the body so that the tumor cannot get the estrogen it needs to grow. This may involve surgery to remove the ovaries (oophorectomy) or, more often, drugs (such as goserelin) to stop the ovaries from producing hormones.
Tamoxifen is also used to treat metastatic 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 may improve survival over either treatment alone [97-98].
Hormone therapy for postmenopausal women
Hormone therapy for postmenopausal women can be tamoxifen (or other anti-estrogen drug) or an aromatase inhibitor. If the first hormone therapy stops working and the cancer starts to grow again, a second drug can be used. If the second drug stops working, another can be tried. At some point—even though it may be years down the line—hormone therapy almost always stops being effective. At this point, chemotherapy may be recommended.
Ovarian suppression is not 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.)
Find a list of hormone therapy drugs commonly used to treat metastatic breast cancer.
Chemotherapy
Chemotherapy is a first treatment for people with hormone receptor-negative tumors and those who have life-threatening metastases. It is also used to treat cancers that no longer respond to hormone therapy. One benefit of chemotherapy is response time. Chemotherapy shrinks tumors sooner 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. With each new drug, though, it is less likely that the cancer will shrink. And, if the cancer does shrink, it often does so for a shorter period of time with each new drug. It is not uncommon for people to have multiple chemotherapy regimens (often five or more) over the course of treatment for advanced breast cancer.
Learn more about chemotherapy.
Find a list of chemotherapy drugs commonly used to treat metastatic breast cancer.
Targeted therapy: Anti-HER2/neu drugs
HER2/neu-positive breast cancer
About 15 to 20 percent of breast cancers have high amounts of a protein called HER2/neu on the surface of the cancer cells (called HER2/neu-positive breast cancer) [65-66]. The HER2/neu protein is important for cancer cell growth.
HER2/neu status is determined by testing the tissue that was removed during biopsy.
Learn more about HER2/neu status.
Trastuzumab (Herceptin)
Trastuzumab (Herceptin) is a specially made antibody that targets HER2/neu-positive cancer cells. When attached to the HER2/neu protein, trastuzumab slows or stops the growth of these cells. Trastuzumab is only used to treat HER2/neu-positive breast cancers. Clinical trials in women with metastatic breast cancer have shown trastuzumab can shrink tumors and slow the growth of cancer when used alone or combined with chemotherapy [99-103].
In some cases, HER2/neu tumors may spread to the brain. Because trastuzumab is not able to cross the blood-brain barrier, it is not used to treat brain metastases.
Side effects and risks of trastuzumab
Trastuzumab causes fewer side effects than chemotherapy. It does not cause hair loss, nausea or vomiting, and has no effect on bone marrow.
In rare cases, deaths due to heart or lung problems have been linked to the use of trastuzumab [66,99]. Although the chance of such an event is small, you should discuss this with your health care provider before starting treatment. Your heart will be checked before and during treatment to help ensure there are no problems.
Lapatinib (Tykerb)
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/neu-positive metastatic breast cancer in women who have already had chemotherapy and trastuzumab. Lapatinib is taken in pill form.
Lapatinib combined with the chemotherapy drug capecitabine (Xeloda) can increase the time before metastatic breast cancer spreads further [104]. And, the results from a recent study showed lapatinib combined with the aromatase inhibitor letrozole may increase time to cancer spread compared to the use of letrozole alone in women with hormone receptor-positive, HER2/neu-positive metastatic breast cancer [105].
Early findings show lapatinib holds promise for HER2/neu-postive metastatic cancer with brain metastases as it can pass through the blood-brain barrier [105-106]. Most therapies, including trastuzumab, cannot cross the blood-brain barrier. In rare cases, lapatinib can help shrink or slow the growth of brain metastases [106-108].
Side effects of lapatinib
Side effects of lapatinib include diarrhea, nausea, vomiting, rash and fatigue. In rare cases, it has been linked to lung problems [109].
Bevacizumab (Avastin)
In November 2011, the FDA revoked its approval for the use of bevacizumab (Avastin) in the treatment of metastatic breast cancer [112]. This action does not affect FDA approval for the use of bevacizumab in the treatment of other types of cancer.
Bevacizumab and other anti-angiogenesis drugs are still under study (learn more).
Updated 01/20/12
