Metastatic brain tumors are the most common type of brain tumors in adults, but account for only about 2% of brain tumors in children.

The U.S. has not established a national reporting system for brain metastases, so estimates of its incidence vary significantly. The most widely accepted estimate suggests about 200,000 new cases are diagnosed each year in the U.S.

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.  It is estimated that as many as 30% of adults, and between 6% and 10% of children, with cancer eventually develop a metastatic brain tumor. Brain metastases occur equally in both men and women.

The symptoms a person may experience are linked to the location of the tumor because the lobes of the brain control different functions, such as thought and reasoning versus vision and hearing.

About 80% of metastatic brain tumors occur in the cerebrum, 15% in the cerebellum, and 5% in the brainstem.

Common symptoms include:

• Headaches
• Seizures
• Speech problems
• Numbness or tingling
• Coordination problems
• Cognitive changes
• Other symptoms can include nausea or vomiting; changes in mood, behavior, or personality; vision changes; and muscle weakness.

Surgery

Traditionally, the most common treatment options for metastatic brain tumors are surgery and radiation therapy. Patients who have surgery may be treated with radiation therapy to improve local disease control. However, targeted therapy and immunotherapy are increasingly being used and are showing promise in helping some patients with metastatic brain tumors. Chemotherapy is not often used to treat brain metastases because the blood-brain barrier prevents many drugs from reaching the brain.

Surgery is often considered as a first option for treating brain metastases if:

• there is one large tumor causing symptoms, the number of tumors is limited,
• all or most of the tumor(s) can be safely  removed,
• there is diagnostic uncertainty,
• the cancer is controlled,
• and the patient is in good overall health.

Surgery also may be recommended if there is a single tumor and the cancer has not spread to other parts of the body.⁴ Some tumors can be removed completely, while others may be reduced in size.

Advances in surgery are making it a safer option for a growing number of people with brain metastases.

Radiation

Radiation therapy is often given following surgery to improve local control. It is also used upfront in many patients when surgery is not feasible. Types of radiation therapy commonly used to treat brain metastases are whole-brain radiation therapy (WBRT) and stereotactic radiosurgery (SRS). Sometimes both types of radiation are used.

SRS is becoming the preferred treatment for patients with a limited number of brain metastases. Patients with brain metastases are increasingly being treated with SRS as studies show it is associated with less cognitive decline than WBRT with no difference in survival.

Chemotherapy

In general, chemotherapy has not been shown to be as helpful as surgery or radiation therapy for treating metastatic brain tumors. That is because most chemotherapy medications are unable to cross the blood-brain barrier to treat the tumors. As a result, chemotherapy is rarely used to treat brain metastases, although there are certain exceptions.

Targeted Therapy and Immunotherapy

Targeted therapies and immunotherapies have been shown to benefit some patients with brain metastases. These options appear to work best for patients with limited, small volume (which refers to the amount of cancer present) disease.

The following targeted therapies, by themselves or in combination, have shown some promise for treating certain specific brain metastases:

• Alectinib, brigatinib, ceritinib, crizotinib, erlotinib, gefitinib, and osimertinib for brain metastases from lung cancer.
• Lapatinib, neratinib, trastuzimab, and tucatinib for brain metastases from breast cancer.
• Dabrafenib, trametinib, and vemurafenib for brain metastases from melanoma.
• Sorafenib and sunitinib for brain metastases from kidney cancer.
• Larotrectinib and entrectinib for tropomyosin receptor kinase fusion-positive brain metastases no matter the type of primary cancer.

 Immunotherapies that have shown promise in treating brain metastases from lung cancer and melanoma are ipilimumab, nivolumab, and pembrolizumab.

Following initial treatment, patients should have an MRI or CT to detect a tumor that has recurred (returned) or to detect new tumors. Typically, patients will be seen one month after the initial therapy and then every two to three months. For as many as half of patients with brain metastases, their tumors will return or they will develop new lesions within six months to one year following initial therapy.

Depending on the patient’s overall condition, and the extent and location of the tumor, treatment options may include surgery, SRS, or WBRT. SRS is increasingly being used to treat recurrent or new tumors that arise after initial therapy for patients who are functioning well and have stable disease. These patients are experiencing local control rates similar to those seen with initial therapy. For some patients who may not be good candidates for surgery or SRS, WBRT may be beneficial.

Surgery may be an option for certain select patients with a large recurrent brain metastasis when the primary cancer is well controlled. Other techniques, such as brachytherapy and LITT, are being studied for treating recurrent brain metastases.