Brain Metastases

What brain metastases are

Cancer cells can break away from the original (primary) tumor, travel in the blood, and settle in the brain, where they grow into new tumors. These are made of the same kind of cells as the primary cancer, so lung cancer in the brain is still lung cancer and is treated as such.

Brain metastases are estimated to occur in up to about 1 in 5 people with cancer during their illness. They may be single or multiple. Sometimes a brain tumor is the first sign of a cancer that has not yet been found elsewhere.

Common primary cancers

• Lung cancer: the most common source, especially small cell and some non-small cell types with specific gene changes (EGFR, ALK).
• Breast cancer: particularly HER2-positive and triple-negative types.
• Melanoma: has a high tendency to spread to the brain.
• Kidney cancer and colorectal cancer.

Symptoms

Symptoms depend on where the metastases are, how large they are, and how much swelling (edema) surrounds them.

• Headache: often worse in the morning, with coughing or bending, and may come with nausea or vomiting.
• Seizures: focal (one limb twitching) or generalized.
• Weakness or numbness on one side of the body.
• Confusion, memory problems or personality and behavior changes.
• Speech or language difficulties.
• Vision problems, such as loss of part of the visual field.
• Balance and coordination problems, especially with tumors in the cerebellum.
• Drowsiness from raised pressure in the skull.

Some brain metastases cause no symptoms and are found on screening or staging scans.

Diagnosis

• MRI with contrast: the best test. It shows the number, size and location of tumors and surrounding swelling.
• CT scan: used in emergencies or if MRI is not possible.
• Body scans: CT or PET-CT to find the primary cancer and other spread.
• Biopsy or surgical removal: confirms the diagnosis when the primary is unknown or the appearance is unusual, and allows testing for genetic markers that guide treatment.
• Lumbar puncture: if spread to the lining of the brain and spinal cord (leptomeningeal disease) is suspected.

Treatment

Treatment is planned by a team including oncologists, neurosurgeons and radiation oncologists. It depends on the number and size of metastases, symptoms, the type of primary cancer and how well it is controlled, and overall health.

Controlling symptoms

• Steroids such as dexamethasone reduce brain swelling and often improve headaches and weakness within days.
• Anti-seizure medicines for people who have had seizures.

Stereotactic radiosurgery (SRS)

Highly focused radiation beams target each tumor while sparing healthy brain. It is now the preferred treatment for a limited number of metastases, given in one to five sessions, with less effect on memory and thinking than whole-brain radiation.

Surgery

Removing a metastasis is considered for a single large tumor, a tumor causing significant pressure or symptoms, or when a diagnosis is needed. Radiation to the surgical cavity usually follows to reduce recurrence.

Whole-brain radiation therapy

Used when there are many metastases or leptomeningeal spread. It can affect memory and thinking, so techniques that spare the hippocampus and the medicine memantine are often used to reduce this.

Drug treatments

• Targeted therapies: some drugs reach the brain well, for example for EGFR- or ALK-positive lung cancer and HER2-positive breast cancer.
• Immunotherapy: checkpoint inhibitors can shrink brain metastases, especially in melanoma and lung cancer.
• Chemotherapy: less effective in the brain for most cancers, but used in some cases.

Outlook

Outlook varies widely. It used to be measured in months, but has improved substantially for many people thanks to radiosurgery, targeted drugs and immunotherapy. People with few metastases, a controlled primary cancer, good general health and a cancer with an effective targeted treatment often live considerably longer, sometimes years. Your oncology team can give a personal estimate based on tools that consider tumor type, number of metastases, age and fitness.

Palliative care specialists can help at any stage with symptom control, emotional support and planning, alongside active treatment.

Living with brain metastases

• Do not drive after a seizure or with certain brain tumors until your doctor says it is safe. Rules vary by state.
• Report new symptoms promptly, as swelling can increase.
• Steroids can cause raised blood sugar, insomnia, increased appetite and mood changes. Your team will taper them when possible.
• Rehabilitation, including physical, occupational and speech therapy, helps with weakness, balance and communication.
• Support for caregivers is important, especially if personality or memory changes occur.

Frequently asked questions

What are the first symptoms of brain metastases?

Common first symptoms are new headaches, often worse in the morning, seizures, weakness or numbness on one side, confusion, personality changes, and speech or vision problems. Some people have no symptoms and the metastases are found on routine scans.

Which cancers spread to the brain most often?

Lung cancer is the most common, followed by breast cancer and melanoma. Kidney and colorectal cancers also spread to the brain. Certain subtypes, such as HER2-positive breast cancer and small cell lung cancer, carry higher risk.

Can brain metastases be cured?

Cure is uncommon because the cancer has already spread, but brain metastases can often be controlled for long periods. A single metastasis treated with surgery or radiosurgery, in someone whose cancer is otherwise well controlled, can sometimes lead to long-term survival.

What is the life expectancy with brain metastases?

It varies widely depending on the type of primary cancer, number of brain tumors, age, overall health and response to treatment. With modern targeted therapy, immunotherapy and radiosurgery, many people live significantly longer than in the past. Your oncologist can give a personal estimate.