Breast cancer can spread beyond its original site, a process known as metastasis. While it can metastasize to various organs, including bones, lungs, and the liver, it can also spread to the brain. This specific spread, referred to as breast cancer brain metastasis, represents an advanced stage of the disease. Approximately 10% to 30% of individuals with metastatic breast cancer may experience this complication.
How Breast Cancer Spreads to the Brain
The journey of breast cancer cells from the breast to the brain involves a complex biological process. Cancer cells detach from the primary tumor and then enter the bloodstream or lymphatic system. Once in circulation, these cells can eventually reach the brain, where they may establish new tumors.
The brain is protected by the blood-brain barrier (BBB), a specialized structure that restricts substance passage from the bloodstream into the brain tissue. However, breast cancer cells have mechanisms to invade and cross this barrier, sometimes even impairing its integrity or forming a “blood-tumor barrier.” Certain molecular subtypes of breast cancer exhibit a higher propensity for brain metastasis. Human Epidermal Growth Factor Receptor 2-positive (HER2-positive) and triple-negative breast cancers (TNBC) are two such aggressive subtypes more frequently associated with spread to the brain. For instance, up to 50% of patients with HER2-positive metastatic breast cancer may develop brain metastases.
Recognizing Brain Metastasis Symptoms
When breast cancer spreads to the brain, it can manifest through a variety of neurological symptoms. Headaches are a common indicator, often described as persistent, progressively worsening, and distinct from typical headaches, sometimes accompanied by nausea or vomiting. Seizures can also occur, ranging from subtle episodes of numbness or tingling to more overt convulsions.
Changes in cognitive function are another important set of symptoms, including memory problems, confusion, or difficulty concentrating. Motor deficits, such as weakness or numbness in the limbs, can also signal brain involvement. Vision problems, speech difficulties, and issues with balance and coordination are also possible. Additionally, personality or mood changes may be observed. Any new or worsening neurological symptoms warrant immediate medical evaluation.
Diagnosing and Treating Brain Metastases
Diagnosing Brain Metastases
Identifying breast cancer brain metastases involves clinical assessment and advanced imaging. A neurological examination is part of the initial evaluation. Magnetic Resonance Imaging (MRI) of the brain with contrast is the most sensitive and preferred imaging technique for detecting these lesions, providing detailed information on their location, size, and number. If MRI is not feasible, Computed Tomography (CT) scans may be used, though they are less sensitive for detecting smaller tumors. A brain tumor biopsy may confirm diagnosis if imaging results are inconclusive.
Treating Brain Metastases
Treatment for breast cancer brain metastases is individualized and often involves a multidisciplinary approach. Local therapies directly target the tumors in the brain. Surgical resection can be an option for accessible tumors, particularly if there are a limited number of lesions. Radiation therapy is a cornerstone of local treatment; Stereotactic Radiosurgery (SRS) delivers highly focused, high-dose radiation to a single or a few small metastases, aiming to spare healthy brain tissue and minimize side effects. Whole-Brain Radiation Therapy (WBRT) treats multiple lesions, though its use is often weighed against potential cognitive side effects.
Systemic therapies aim to control cancer cells throughout the body, including those in the brain. Chemotherapy agents face challenges in penetrating the blood-brain barrier, but some drugs like capecitabine, platinum compounds, and temozolomide have shown some ability to cross it. Targeted therapies are particularly relevant for specific breast cancer subtypes, such as HER2-positive disease, with agents like trastuzumab deruxtecan and tucatinib demonstrating activity against brain metastases by overcoming the blood-tumor barrier. Immunotherapy is an emerging treatment option, especially for certain subtypes like TNBC. The choice of treatment depends on factors such as the number and size of lesions, the patient’s overall health, and the specific molecular characteristics of the breast cancer.
Living with Brain Metastases
Managing breast cancer brain metastases includes supportive care aimed at improving quality of life. Corticosteroids, such as dexamethasone, are prescribed to reduce brain swelling and pressure, which can alleviate symptoms like headaches and nausea. Anti-seizure medications may prevent or control seizures.
Rehabilitation therapies address neurological deficits. Physical therapy can help with motor weakness and balance issues, while occupational therapy assists with daily activities affected by cognitive or physical changes. Speech therapy supports individuals experiencing difficulties with communication.
Beyond physical well-being, psychological and emotional support is important for both patients and their families, often involving counseling or participation in support groups. Palliative care, which focuses on symptom management and enhancing overall quality of life, can be integrated early in the treatment journey, working alongside curative therapies. Advances in treatments and supportive care have improved outcomes and quality of life for individuals navigating breast cancer brain metastases.