Breast cancer sometimes metastasizes (spreads) to the brain. This condition is commonly referred to as "secondary breast cancer in the brain." Brain metastases occur in approximately 10%-15% of women with stage 4 breast cancer. In some cases, the breast cancer metastasizes directly to the brain; in others, the breast cancer metastasizes to another area of the body—such as the lungs, liver or bones—before it reaches the brain.
Some people assume that a brain metastasis is brain cancer. However, that’s not the case. The distinction between brain cancer and brain metastases lies in where the cancer originated—brain cancer involves tumors made up of cancerous brain cells, while brain metastases involve tumors made up of cancerous cells from elsewhere in the body (e.g., cancerous breast cells).
If breast cancer metastasizes to the brain, it can cause a variety of symptoms to develop, including:
- Memory loss
- Changes in mood, personality or behavior
- Impaired judgment
- Balance problems
- Weakness or paralysis in one side of the body (hemiparesis)
- Numbness or tingling within the extremities
- Changes in vision, such as blurred vision, double vision, loss of vision or seeing flashes of light
- Slurred speech
If a physician suspects that a patient’s breast cancer has metastasized to the brain, he or she will likely order a magnetic resonance imaging (MRI) scan to confirm the diagnosis. In many cases, the MRI will be performed using contrast solution, which can make the resulting images clearer. A computed tomography (CT) scan may be used as an alternative if an MRI is not feasible.
Less often, the physician will order a biopsy to confirm the diagnosis. This diagnostic procedure involves drilling a small hole into the patient’s skull, removing a sample of the brain lesion using a narrow needle and then sending the sample to a laboratory for examination by a pathologist.
Younger women—especially those younger than 35 at the time of their breast cancer diagnosis—are at a greater risk for developing brain metastases. Other risk factors include having a breast tumor that’s larger than 2 cm in diameter and having positive lymph nodes at the time of the initial diagnosis.
Aggressive types of breast cancer, such as HER2-positive breast cancer and triple-negative breast cancer, are also more likely to metastasize to the brain. Breast cancer cells commonly have receptors for the protein human epidermal growth factor receptor 2 (HER2) and the female hormones estrogen and progesterone. Breast cancer cells that have abnormally high levels of HER2 are referred to as HER2-positive. Breast cancer cells that do not have HER2, estrogen or progesterone are referred to as triple-negative.
It’s important to remember that these are risk factors for brain metastases. As such, the fact that a breast cancer patient is under the age of 35 or has HER2-positive or triple-negative breast cancer means that brain metastasis is more likely to occur, not that it will definitively happen.
Once breast cancer has spread to the brain or any other distant area of the body, it’s considered to be stage 4 breast cancer. Researchers in the general medical community are still working to find a cure for breast cancer that has progressed to this stage. As treatment options continue to advance, however, patients are achieving better outcomes and quality of life.
Before discussing appropriate treatments for brain metastases, it can be helpful to understand the difference between local therapy and systemic therapy. Local therapy refers to treatments that affect a specific area of the body (examples include surgery and radiation therapy). Systemic therapy, on the other hand, refers to treatments that affect the entire body (examples include chemotherapy and hormonal therapy).
Generally, breast cancer that has metastasized (whether to the brain or another area of the body) is best treated using systemic therapy. However, in certain situations, local therapy may be used to treat metastatic breast cancer. For many patients, treatment of brain metastases is focused on slowing the growth of the malignancy and relieving the resulting symptoms.
Brain metastases vs. leptomeningeal metastases
While brain metastases refer to cancer that has spread to the brain, leptomeningeal metastases refer to cancer that has spread to the tissues and fluid surrounding the brain and spinal cord. Although the symptoms of leptomeningeal metastases are similar to those of brain metastases, they are often less obvious and thus more challenging to diagnose. Physicians often confirm a diagnosis using MRI scans, but in some cases they may also order a lumbar puncture, which involves inserting a needle into the spine and collecting a fluid sample to be examined by a pathologist in a laboratory.
If you’d like to know more about breast cancer metastasis to the brain, you can get the answers you need from the team of experts at Moffitt Cancer Center. The multispecialty team in our Don & Erika Wallace Comprehensive Breast Program—which includes experienced surgeons, medical oncologists, pathologists, radiologists, radiation oncologists, plastic surgeons, breast reconstruction experts, social workers, fertility preservation specialists and genetic testing and counseling specialists—collaborate to provide our patients with the highly individualized care they need and deserve.
To request a consultation at Moffitt Cancer Center, call us at 1-888-663-3488 or complete our new patient registration form online. We’ll be happy to arrange a time for you to meet with one of the specialists on our team.