Metastatic brain tumors

What is it?

A metastatic brain tumor is cancer that has spread (metastasized) from another part of the body to the brain. It is also called a secondary tumor, lesion, or brain metastasis (plural: metastases). In contrast, a primary brain tumor starts in the brain, not in another part of the body.

A tumor is an abnormal mass of tissue. It occurs when cells divide more than they should or don't die when they should.

Cancers that spread to the brain can originate in any part of the body. The original tumor is called the primary tumor. Metastatic brain tumors most commonly originate in the lung, breast, skin, colon, and kidney. A very aggressive form of skin cancer called melanoma often spreads to the brain.

Brain metastases occur when cancer cells break away from a primary tumor. They travel to the brain, usually through the bloodstream. These cancer cells may settle in the brain and continue growing. Sometimes only one secondary brain tumor occurs. But in many cases there are multiple lesions.

The brain is a complex organ enclosed in the skull. Among other things, it serves as the body's center of

• thought
• memory
• emotion
• speech
• vision
• hearing
• movement.

Symptoms

The signs and symptoms of secondary brain tumors depend on their size and location. This is because different parts of the brain control different functions.

As a tumor grows, it can press against or destroy normal brain tissue. It can also increase pressure inside the skull.

Signs and symptoms of brain metastases include

• headaches
• seizures
• visual changes, such as double vision
• lack of energy and/or sleepiness
• vomiting
• changes in mood, behavior, or personality
• weakness in parts of the body
• trouble speaking or hearing
• problems with memory or mental ability
• loss of balance or coordination.

These symptoms are not necessarily signs of brain metastases. But it is important to contact your doctor if you experience any of them.

Some people with metastatic brain tumors don't show any symptoms. However, over time, the brain metastases will continue to grow, eventually causing symptoms.

Diagnosis

The first step in diagnosis is usually a physical exam. Your doctor will check for general signs of disease. He or she will also ask about your health habits and past illnesses and treatments.

The following tests and procedures may be used to determine whether you have cancer that has spread to your brain.

Neurological and visual exams. These tests assess your mental and physical abilities, including

• alertness
• muscle strength
• coordination
• reflexes
• response to pain
• eyesight.

Tumor marker test. A sample of blood, urine, or tissue is taken. Levels of certain substances that may indicate the presence of cancer are measured.

Imaging tests:

• Computed tomography (CT) scan. An x-ray camera rotates around the body. It makes detailed, cross-sectional images of the brain.
• Magnetic resonance imaging (MRI). Radio waves and strong magnets produce detailed pictures of the brain. MRI is better than CT at finding metastatic brain tumors.
• Positron emission tomography (PET) scan. Radioactive glucose (sugar) is injected into the patient's vein. A rotating scanner highlights areas where cells are consuming the glucose. (Cancer cells use more glucose than normal cells.) PET scans may be used before or after treatment.

Lumbar puncture (spinal tap). Assuming it can be done safely, the doctor may want to remove cerebral spinal fluid from the lower back with a needle in some cases. The fluid is then checked for cancer cells.

Angiogram. A contrast dye is injected into the bloodstream and x-rays are taken. This allows the doctor to examine blood vessels and blood flow in the brain. It may identify blockages such as tumors. However, this procedure is less common than in the past because MRI can often provide the same information.

Biopsy. A small piece of tumor tissue is removed for examination. The tumor tissue may be tested for certain substances that provoke an immune response. It will also be analyzed for changes in the cells and their genetic material.

Biopsy can be done using a needle inserted through a hole in the skull. Or it may be done during surgery to remove a tumor.

Sometimes a biopsy can't be done safely because of the tumor location. In this case, the doctor uses imaging and other tests to make the diagnosis.

Sometimes the primary cancer is discovered after the patient is diagnosed with metastatic brain tumors. If brain lesions are the first sign of cancer, various imaging tests may be done to search for the primary tumor.

Expected duration

Primary cancers spread to the brain at different rates. For example, lung cancer tends to spread to the brain much sooner than many other cancers. The tumors will continue to grow until they are treated.

Prevention

Some metastatic brain tumors develop from common cancers that begin in organs. Surgeons may be able to remove part or all of such tumors. Therefore, surgery is one way to prevent a cancer from spreading to the brain.

Treatment

Treatment for metastatic brain tumors may include surgery, radiation therapy, immunotherapy, and/or chemotherapy.

The treatment approach depends on the

• type of primary cancer
• number and location of brain lesions
• extent of the primary cancer
• patient's general health.

Whether the patient received chemotherapy and the response will also influence decisions about treatment.

Surgery

Some patients have only one secondary brain tumor that can be easily reached. In this case, surgery is the preferred treatment.

Surgery removes or reduces the size of the tumor. It can also help ease symptoms caused by pressure and swelling in the brain. This is true even if the tumor is not removed completely.

Radiation therapy

Radiation therapy is typically recommended when

• there are multiple brain metastases
• single tumors can't be surgically removed
• tumor cells may remain after surgery.

Radiation therapy uses high-energy x-ray beams to damage or destroy tumor cells. It is usually delivered by a machine outside the body. This is called external beam radiation. Different types of radiation therapy may be given individually or together.

Whole brain radiation therapy (WBRT) delivers an even dose of radiation to the entire brain. Side effects may include

• fatigue
• nausea
• vomiting
• headache
• memory loss.

In addition, dead tumor cells may build up in the brain.

Radiosurgery (also called stereotactic radiosurgery) is a more targeted procedure. It delivers radiation beams to a precise location in the brain. Despite its name, radiosurgery does not involve surgery. It is less likely than whole brain radiation to harm healthy brain tissue. It typically causes fewer side effects, too.

Immunotherapy

Certain cancers that have spread to the brain have shown responses to immunotherapy. Some patients with brain metastases from melanoma and lung cancer have had clinically significant improvement with this therapy.

Chemotherapy

Chemotherapy is the use of drugs to stop the growth of cancer cells. For most types of metastatic brain cancer, it is less effective than surgery or radiation. Significant side effects are more likely to occur if the patient receives both radiation and chemotherapy.

Symptom relief

Medicines and other therapies may help manage symptoms and improve quality of life. They include

• steroids to reduce brain swelling
• antiseizure medications (anticonvulsants)
• pain medication
• complementary therapies, such as stress management, imagery training, meditation, or counseling
• physical and occupational therapy.

When you are considering a treatment option, ask your doctor about the risks and potential benefits. How will this treatment affect my prognosis? What will my quality of life be during and after treatment?

New therapies for metastatic brain tumors are being tested in clinical trials. You may want to consider joining a clinical trial if you find one that fits your medical and personal situation.

When to call a professional

Contact your doctor if you experience symptoms of metastatic brain tumors, including

• seizures
• headaches
• weakness in areas of the body
• lack of energy
• vomiting
• changes in mood, behavior, or personality
• speech, vision, or hearing difficulties
• problems with memory or mental ability
• loss of balance or coordination.

Prognosis

The outlook for patients with brain metastases depends on

• the patient's age
• the number and location of the tumors
• how well the tumors respond to treatment
• whether the primary tumor is still growing and spreading.

People with secondary tumors that began with breast cancer have a better outlook than those with other types of primary cancer.

Cancer can be fatal even if it does not spread. However, most people who die of cancer have metastases.

Additional info

National Cancer Institute (NCI)
https://www.cancer.gov/

American Cancer Society (ACS)
https://www.cancer.org/

American Brain Tumor Association
https://www.abta.org

National Brain Tumor Society
https://braintumor.org/