A metastatic brain tumor, also referred to as a brain metastasis or secondary brain tumor, refers to cancer that begins elsewhere in the body (primary cancer site) and spreads (metastasizes) to the brain. Brain metastasis can be a single tumor or multiple tumors.
While any cancer can spread throughout the body and brain, cancers that most commonly metastasize to the brain include lung cancer, breast cancer, melanoma (skin cancer), colon cancer and kidney cancer.
- The incidence of metastatic brain tumor diagnosis is estimated at about 200,000 people annually.
- About 60% of patients who are diagnosed with brain metastases are between the ages of 50 and 70 years, with a peak incidence at 60 years of age.
- Central nervous system (CNS) metastasis is not common in children,
accounting for only 6% of CNS tumors in children.
- Research indicates approximately 10–20% of metastatic brain tumors arise as a single tumor and 80+% as multiple tumors within the brain.
- About 85% of metastatic brain tumors are located in the cerebrum (the top, largest component of the brain) and 15% are located in the cerebellum (the bottom, back part of the brain).
Metastatic brain tumors begin when cancer located in another organ of the body spreads to the brain.
Metastasis occurs when cancer cells from a tumor break away and are carried to other parts of the body through the bloodstream or lymphatic system. The immune system attempts to destroy these migrating cancer cells. However, if the number of cancer cells becomes very high, the immune system may become overwhelmed or tolerant of these cells.
The symptoms of a metastatic brain tumor are the same as those of a primary brain tumor, and are related to the location of the tumor within the brain. Each part of the brain controls specific body functions. Symptoms appear when areas of the brain can no longer function properly.
Most Common Symptoms
- Coordination problems
- Cognitive challenges
- Nausea or vomiting
- Changes in mood, behavior, or personality
- Vision changes
The main categories of treatment include surgery, radiation and medical therapy (chemotherapy, targeted therapy or immune-based therapy). More than one type of treatment may be suggested. Types of treatment may be selected based on several factors, including type of primary cancer, number of tumors, tumor size and location, and the patient’s overall health.
Early treatment will focus on controlling symptoms, such as swelling of the brain and/or seizures. Treatment may include use of:
- Steroids such as dexamethasone or decadron. These are drugs used to reduce the swelling that can occur around a brain tumor. Reducing the swelling in the brain can reduce the raised brain pressure, and thus temporarily reduce the symptoms of a metastatic brain tumor.
- Antiepileptic (anti-seizure) drugs such as levetiracetam, phenytoin, or lacosamide are commonly used to control seizures.
Single or Limited Brain Metastases
Surgery is preferred when there are a limited number of brain metastases (generally one to three tumors.) Removing a tumor surgically can help reduce symptoms and confirm diagnosis. Radiation therapy may be used in addition to, or in place of surgery. The goal of radiation is to shrink or slow the growth of the tumor(s). Stereotactic radiosurgery is the most common type of radiation therapy used for a limited number of small (less than 3 cm) brain metastases. In some cases, medical therapies such as chemotherapy, targeted therapy, or immunotherapy may be suggested. The use of medical treatments depends on the patient’s primary cancer type or the tumor’s molecular markers.
Multiple Brain Metastases
If there are multiple brain metastases—four or more brain tumors—surgery may be used to confirm diagnosis or reduce symptoms. More commonly, radiation is used to shrink or slow the growth of the tumors. Stereotactic radiosurgery is often used to treat a limited number of small brain metastases. If there is an extensive number of tumors, or the primary cancer is not controlled, whole-brain radiation therapy may be used. In some cases, medical therapies such as chemotherapy, targeted therapy, or immunotherapy may be suggested. The use of these medical treatments depends on the patient’s primary cancer type or the tumor’s molecular markers.