About 10-15% of women with stage IV breast cancer develop brain metastases. For most, the breast cancer has already traveled to another part of the body, such as the bones, liver, or lung. However, for about 17% of women in this group, the brain is the only site of metastasis.
The risk of cancer spread to the brain is usually highest for women with more aggressive subtypes of breast cancer, such as HER2-positive or triple-negative breast cancer.
Symptoms of breast cancer in the brain can include:
- changes in senses controlled by the brain such as slurred speech, blurred vision, balance problems, dizziness, or anything else that seems unusual
- memory problems
- mood or personality changes
- stroke or “brain attack,” in which blood supply to the brain is cut off; symptoms can include sudden weakness or numbness on one side of the body, headache, trouble speaking, vision changes, dizziness and/or loss of balance
If your doctor suspects brain metastasis, he or she will order an MRI (magnetic resonance imaging) study of the brain, often with contrast solution. This solution is delivered intravenously and then travels into the brain, helping to make the study images clearer. Usually, an MRI can determine whether an unusual finding in the brain is metastatic breast cancer.
In rare cases, biopsies are performed to confirm the diagnosis. To obtain a biopsy specimen, a surgeon drills a small hole through the skull and uses a narrow, hollow needle to remove a sample of the brain lesion. Imaging studies can help the surgeon direct the needle to the precise area. The sample is sent to a pathologist for examination.
The most common treatments for metastatic breast cancer in any location (bone, brain, lung, or liver) are systemic medications, which treat cancer throughout the entire body. Systemic medications include chemotherapy, hormonal therapy, targeted therapies, and bone-strengthening medication.
Local treatments — therapies directed specifically to the new locations of the breast cancer — aren’t usually the first choice for metastases. Still, local treatments are recommended under certain circumstances. Local treatments include surgery and radiation therapy.
You can read about systemic and local treatments for metastasis in the Recurrent and Metastatic Breast Cancer Treatment Choices section.