Metastatic Brain Tumor
A metastatic brain tumor forms from cancer cells that spread to the brain, after originating from a tumor elsewhere in the body.
For example, about half of all metastatic brain tumors are from lung cancer cells that entered the bloodstream and spread into the brain.1 Other cancers that commonly spread to the brain include melanoma, breast cancer, colon cancer, and kidney cancer.
Metastatic brain tumors can occur as a single tumor (also called brain metastasis) or as multiple tumors (brain metastases) throughout the brain and spinal cord. Another type of metastatic cancer is described as leptomeningeal, when it occurs in the meninges (the membranes that cover the brain and spinal cord) or in the cerebrospinal fluid (the fluid in the brain and spinal cord that cushions the brain within the skull).
Metastatic tumors are usually discovered when a cancer patient begins experiencing neurological symptoms, although in some cases metastatic brain tumors are found as the first symptoms of a cancer.
Some of the most common symptoms include the following:
- Cognitive changes (including memory problems, changes in personality or behavior)
- Intracranial bleeding or hemorrhage
- Gait or balance changes
Additional symptoms may occur, depending on size and location of the tumor. For example, if the tumor is located near the parts of the brain that control body movement, subsequent symptoms might include muscle weakness in parts of the brain, or difficulties in walking.
Metastatic brain tumors are the most common brain tumor in adults, outnumbering primary brain tumors (those that arise in the brain) by at least 10 to 1.2 In fact, brain metastases occur in an estimated 20-40% of adult cancer patients.2 In contrast, metastatic brain tumors are rare for pediatric patients with solid tumors. However, in cases of pediatric leukemia, cancerous cells may spread to the brain and spinal cord.
Patients with metastatic brain tumors may be treated with a combination of surgery, radiation therapy, and medical therapy. A patient’s specific treatment plan may depend on a variety of factors, including the following:
- Number of brain metastases
- Size of brain metastases
- Location of brain metastases
- Overall health and cancer history
For patients with a limited number of brain metastases (typically one to five tumors), treatment typically involves a combination of surgery, radiotherapy, and medical therapy. Surgery may be performed to remove as much of the tumor(s) as possible, and confirm diagnosis. Radiation therapy may involve stereotactic radiosurgery (like Gamma Knife) which focuses a high dose of radiation specifically within smaller tumor sites. Medical therapy may follow, including chemotherapy or immunotherapy to treat both the brain metastatic tumor(s) and primary cancer, if needed.
For patients with multiple brain metastases (typically five or more tumors), a common treatment includes whole brain radiation. The goal of whole brain radiation is to treat not only the visible brain metastases, but also the microscopic metastases that may be too small to be detected. Increasingly, stereotactic radiosurgery and medical therapy may also be used for patients with multiple brain metastases.
Depending on the patient’s primary cancer, certain medical therapies might be more or less effective. For example, preliminary evidence suggests that brain metastases from melanoma and non-small cell lung cancer are more susceptible to immunotherapy.3 Some targeted drug therapies specifically target small cell lung cancer, breast cancer, and lymphoma.
Together, the combination of therapies in a patient’s personalized treatment plan is meant to not only increase long-term survival of the patient, but also to maximize the patient’s quality of life by addressing specific symptoms and preserving cognitive function.
Metastatic brain tumors are a serious condition that will be treated by a multidisciplinary team consisting of neurosurgeons, oncologists and radiation oncologists. How well the tumors respond to treatment depends on a variety of factors, including the number and size of the brain metastases, the type and status of the primary cancer, and the patient’s overall health. Patients will be monitored for metastatic brain tumors that recur after treatment, and additional therapies will be recommended as needed.
The primary goal of treatment is to not only prolong survival for patients, but also to increase a patient’s quality of life, by addressing neurological symptoms and preserving cognitive function.
- Nayak, L., E.Q. Lee, and P.Y. Wen, Epidemiology of brain metastases. Curr Oncol Rep, 2012. 14(1): p. 48-54.
- Patchell, R.A., The management of brain metastases. Cancer Treatment Reviews, 2003. 29(6): p. 533-540.
- Tan, A.C., et al., Immune Checkpoint Inhibitors for Brain Metastases. Curr Oncol Rep, 2017. 19(6): p. 38.
This content was reviewed by UCSF Neuro-Oncology Fellow, Robin Buerki MD.