Breast Cancer Metastasis to the Brain

Breast cancer metastasis to the brain differs from primary brain cancer, which begins in the brain itself. In this advanced stage, cancer cells break away from a primary breast tumor, travel through the bloodstream or lymphatic system and form secondary tumors in the brain. This complication affects approximately 10 to 15% of women with stage 4 breast cancer and can develop months or even years after the initial diagnosis, underscoring the importance of ongoing monitoring and coordinated care.

What are the symptoms of breast cancer metastasis to the brain?

Metastatic breast cancer can interfere with various neurological functions depending on the location, size and number of brain tumors. Symptoms, which can appear suddenly or develop gradually, may include:

• Severe or persistent headaches
• New-onset or worsening seizure activity
• Nausea and vomiting, especially in the morning
• Visual disturbances, such as blurred or double vision
• Impaired balance or coordination
• Numbness or muscle weakness, often on one side of the body
• Cognitive changes, such as mental confusion, memory issues or trouble concentrating
• Behavior or personality changes
• Speech or language difficulties

How is breast cancer metastasis to the brain diagnosed?

Diagnosing brain metastasis in a patient with a history of breast cancer typically begins with a clinical evaluation based on the neurological symptoms. If the patient reports persistent headaches, vision changes, seizures or other signs that suggest brain involvement, the physician will perform a thorough medical history review and physical examination, including a neurological assessment. The diagnostic process may include:

Imaging studies used to diagnose breast cancer metastasis to the brain

The primary tool for diagnosing brain metastasis is advanced imaging. Common tests include:

• Magnetic resonance imaging (MRI) – The most sensitive and preferred imaging technique for detecting brain metastasis, MRI can reveal the location, size and number of tumors in high detail and may be enhanced with contrast dye for enhanced visualization.
• Computed tomography (CT) – If MRI is not feasible or available, a CT scan may be ordered, especially in an emergency. However, computed tomography is less sensitive than magnetic resonance imaging in detecting small or hidden tumors.

Procedures used to diagnose breast cancer metastasis to the brain

In certain cases, the physician may order a diagnostic procedure, such as:

• Lumbar puncture (spinal tap) – If the physician suspects leptomeningeal disease, which occurs when cancer has spread to the membranes surrounding the brain and spinal cord, a sample of cerebrospinal fluid (CSF) may be collected and examined for cancer cells.
• Biopsy – If imaging tests are inconclusive or the diagnosis is uncertain, a neurosurgeon may perform a biopsy of the brain tumor to check for breast cancer metastasis.

If breast cancer metastasis to the brain is confirmed, additional testing may be performed to help the physician assess the extent of cancer spread and plan treatment. A prompt and accurate diagnosis is essential for initiating appropriate care and improving symptom control.

What are the risk factors for breast cancer metastasis to the brain?

Researchers have identified several factors that may increase the likelihood of breast cancer metastasis to the brain. These include:

• Breast tumor type – Certain types of breast cancer tend to be aggressive and more likely to spread to the brain, such as triple-negative breast cancer (TNBC), especially within the first few years after diagnosis, and HER2-positive breast cancer, even in patients who respond well to initial treatment.
• Breast cancer stage – Patients diagnosed with stage 3 or 4 breast cancer are at heightened risk of metastasis to distant organs, including the brain.
• Young age at the time of diagnosis – Women diagnosed with breast cancer at a young age (generally under 35) may have more aggressive tumor biology, which has been linked to a higher risk of brain metastasis.
• Metastasis elsewhere in the body – Patients whose cancer has already spread to other distant sites, such as the lungs, liver or bones, have a greater likelihood of developing brain metastasis later.
• Genetics – While research is ongoing, experts believe certain genetic mutations, such as those affecting breast cancer gene 1 (BRCA1), may play a role in increasing the risk of breast cancer metastasis to the brain and other organs.
• Length of time since initial diagnosis – The longer a patient lives with breast cancer, the more time the tumor has to spread to other parts of the body, including the brain.

What is the prognosis for breast cancer metastasis to the brain?

Brain metastasis is a serious complication of advanced breast cancer, and several factors can influence the prognosis. These include:

• Breast tumor type – Patients with HER2-positive breast cancer may have a better outcome than those with triple-negative breast cancer, primarily due to the availability of effective targeted therapies.
• Number of metastases – Individuals with a single or limited number of brain lesions may have a more favorable prognosis than those with widespread brain involvement.
• Performance status – A patient’s overall physical health and ability to carry out daily activities (performance status) can significantly impact their treatment options, outcome and quality of life.
• Response to treatment – Patients who respond well to surgery, radiation therapy and/or systemic therapy often have a good outcome.
• Control of extracranial disease – Patients whose cancer outside the brain is well controlled tend to have a better prognosis.

How is breast cancer metastasis to the brain treated?

Treatment for breast cancer metastasis to the brain focuses on relieving symptoms, controlling cancer spread and maintaining quality of life. The treatment plan should be tailored to the patient based on the location, size and number of brain lesions as well as the type of breast cancer and the patient’s overall health. Options may include:

• Stereotactic radiosurgery (SRS) – A highly focused form of radiation therapy, SRS can target one or a few small tumors with minimal impact on the surrounding healthy tissues.
• Whole-brain radiation therapy (WBRT) – Sometimes used when multiple brain metastases are present, WBRT treats the entire brain and may help prevent the development of new lesions.
• Surgery – Neurosurgery may be considered to remove one or more accessible tumors, especially if they are causing neurological symptoms by creating pressure or swelling in the brain. Surgical treatment is usually followed by radiation therapy to help prevent recurrence.
• Targeted therapy – HER2-positive breast cancer may be treated with specialized medications, such as tucatinib, trastuzumab and lapatinib, which are designed to penetrate the blood-brain barrier.
• Hormonal therapy – Endocrine therapy may be considered for hormone-receptor-positive breast cancer, although it is generally less effective in treating brain metastasis.
• Chemotherapy – Certain chemo medications can reach the brain and may be used to address active systemic disease.
• Immunotherapy – A biological therapy that capitalizes on the power of the body’s immune system to fight cancer, immunotherapy may be an option for a patient with triple-negative breast cancer, especially if the tumors express certain immune markers, such as PD-L1.
• Corticosteroids and anti-seizure medications – Often used to manage brain metastasis symptoms, corticosteroids can reduce brain swelling to ease headaches and neurological symptoms, while anti-seizure drugs may be prescribed if seizures are present or likely.
• Clinical trials – Through these important research studies, patient participants can benefit from promising new brain metastasis treatment options that are not yet available in other settings.

Brain metastasis vs. leptomeningeal metastasis

Brain metastasis and leptomeningeal metastasis both involve the spread of cancer to the central nervous system (CNS). However, each affects a different area of the CNS and requires a distinct approach to diagnosis and treatment.

Brain metastasis develops when cancer cells spread from another part of the body and form tumors within the brain tissue itself. Leptomeningeal metastasis occurs when cancer cells spread to the thin layers of tissue (leptomeninges) that cover the brain and spinal cord and circulate in the cerebrospinal fluid (CSF). Unlike brain metastasis, which forms solid tumors, LMD involves more diffuse cancer spread and can affect multiple areas of the CNS.

Although the symptoms of leptomeningeal metastasis can be similar to those of brain metastasis, they are usually less obvious and therefore more challenging to diagnose. In addition to using MRI scans, the physician may order a lumbar puncture to confirm the diagnosis.

Benefit from world-class care at Moffitt Cancer Center

If you would like to learn more about breast cancer metastasis to the brain, you can request an appointment with a specialist in Moffitt’s Neuro-Oncology Program by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.