Melanoma is an aggressive type of skin cancer originating from pigment-producing cells called melanocytes. When the disease progresses, cancer cells can travel through the bloodstream to establish new tumors in distant organs. The spread of melanoma to the central nervous system (CNS), which includes the brain and spinal cord, represents an advanced stage of the disease. Melanoma is the third most common cancer to metastasize to the brain, following lung and breast cancers. Historically, this diagnosis carried a poor outlook, but advancements in treatment have significantly changed the landscape of managing advanced melanoma.
Recognizing the Signs of Brain Metastasis
The symptoms that arise when melanoma spreads to the brain are primarily caused by the physical presence of the tumor lesions and the surrounding inflammatory swelling, known as edema. These masses occupy space within the confined skull, which increases intracranial pressure and interferes with normal brain function. This mechanism, referred to as mass effect, means the resulting symptoms depend on the size and exact location of the metastatic tumors.
A new onset headache is the most frequent symptom. These headaches may be accompanied by nausea and vomiting, especially in the morning, due to the pressure changes within the brain. Focal neurological symptoms, which affect a specific area of the body, can manifest as weakness or numbness on one side of the body.
Cognitive changes, such as memory loss, confusion, or difficulty with concentration, may also signal brain metastases. The irritation caused by the tumor tissue can trigger seizures, which are the initial sign in a significant portion of patients. Vision problems, including double vision or a loss of peripheral sight, can occur if the tumors are located in areas controlling visual processing.
Diagnostic Procedures for Confirmation
When a patient with a history of melanoma exhibits new neurological symptoms, a comprehensive neurological examination is performed to assess reflexes, coordination, balance, and cognitive status. This initial assessment helps pinpoint which areas of the brain might be affected. To confirm the presence and characteristics of any lesions, advanced medical imaging is required.
Magnetic Resonance Imaging (MRI) of the brain with an injected contrast agent is the most effective imaging method for detecting melanoma metastases. MRI provides detailed images of soft tissues, allowing physicians to determine the size, number, and location of the tumors. Melanoma lesions often have a distinctive appearance on MRI due to the presence of melanin and a tendency toward hemorrhage.
Computed Tomography (CT) scans may also be used, particularly when an MRI is contraindicated. In cases where the diagnosis remains uncertain, a stereotactic biopsy may be performed to collect a tissue sample for laboratory analysis. However, if the patient has a confirmed advanced melanoma diagnosis, imaging alone is often sufficient to establish the diagnosis of brain metastasis.
Treatment Strategies for Brain Metastases
The approach to treating melanoma brain metastases involves a multidisciplinary team. Treatment selection depends on the number and size of the lesions, their location, and the patient’s overall health. Local treatments manage tumors within the brain, while systemic therapies target cancer cells throughout the body.
Surgical Resection
Surgical resection is an option primarily for patients with a single, large, and easily accessible metastatic lesion. Removing the tumor can immediately relieve symptoms caused by mass effect and provides tissue for analysis. Following surgical removal, radiation therapy is often administered to the tumor bed to minimize the risk of local recurrence.
Radiation Therapy
Radiation therapy is a primary local treatment, with two main forms used. Stereotactic Radiosurgery (SRS) delivers focused, intense doses of radiation to a limited number of small tumors, sparing surrounding healthy brain tissue. This technique is favored for its lower risk of neurocognitive side effects.
Whole Brain Radiation Therapy (WBRT) treats the entire brain with lower doses of radiation over multiple sessions. WBRT is typically reserved for patients with numerous metastases or when SRS is not feasible. While it treats both visible tumors and microscopic disease, WBRT carries a higher risk of long-term cognitive decline.
Systemic Therapies
Modern systemic therapies have improved outcomes because these agents can penetrate the blood-brain barrier. Immunotherapy, particularly checkpoint inhibitors, can unleash the body’s immune system to attack cancer cells in the brain. Combination immunotherapy often yields high response rates and prolonged survival in patients with asymptomatic brain metastases.
Targeted therapy is an option for tumors that harbor specific genetic alterations, such as the BRAF V600 mutation, present in about half of all melanomas. The combination of a BRAF inhibitor and a MEK inhibitor is effective against these mutated cells. These systemic treatments are often combined with local therapies like SRS to achieve the best possible control of the disease.
Managing Quality of Life and Prognosis
While the diagnosis of melanoma brain metastasis indicates advanced disease, the prognosis has improved with modern treatments. Historically, the median survival was only a few months, but dual immunotherapy and targeted therapies have led to longer survival. Factors such as the number and size of brain lesions, the patient’s overall physical condition, and the tumor’s response to systemic therapy influence the long-term outlook.
Supportive care, also called palliative care, should be initiated early in the disease course. Palliative care specialists focus on managing symptoms and improving the patient’s overall quality of life. This includes addressing treatment side effects and the neurological symptoms caused by the brain tumors.
Corticosteroids are used to reduce the inflammatory edema surrounding the metastases, which relieves symptoms like headaches and neurological deficits. Anti-seizure medications are also prescribed to prevent or control seizures that may arise from tumor irritation. The multidisciplinary care team ensures that all aspects of the patient’s physical and emotional well-being are addressed.