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Brain metastases are also much more common. An estimated 150,000 to 200,000 people are diagnosed with a brain metastasis each year, compared to about 17,000 diagnoses for primary brain tumors.
The number of brain metastasis diagnoses has actually risen recently. Many doctors believe this is due to better early detection of brain metastases, as well as better treatments for primary cancers. As more people live longer with a primary cancer, the disease has more time to spread to the brain. This has led to a renewed focus on treating brain metastases.
Any cancer can spread to the brain, but the three most likely to do so are breast cancer, lung cancer and melanoma. Other cancers that often spread to the brain include colon cancer, gynecologic cancers and renal cell carcinoma.
A cancer can metastasize (or spread) to a single location or to multiple locations in the brain. It can also spread to the cerebrospinal fluid or to the leptomeninges, the outer lining of the brain and spinal cord. This type of metastasis is known as leptomeningeal disease (LMD), or leptomeningeal carcinomatosis.
Since LMD cancer cells float in the cerebrospinal fluid, they can quickly spread throughout the central nervous system. As a result, LMD has a poor prognosis.
Brain function and anatomy
The brain processes all our senses and is the starting point of our emotions and movements. It sends and receives messages throughout the body via the spinal cord and nerves in the head. The network of the brain and spinal cord is called the central nervous system (CNS).
The brain is protected by the skull, while the vertebrae of the spine protect the spinal cord. Extra protection is provided by a liquid called cerebrospinal fluid, which surrounds both the brain and the spinal cord.
The brain has four main parts:
Cerebrum: The cerebrum is outer and largest part of the brain. It has two halves that are called hemispheres. Each hemisphere has four lobes: a frontal lobe, parietal lobe, temporal lobe and occipital lobe. The cerebrum is responsible for our senses of sight, hearing, smell and touch, as well as emotional reasoning language and movement.
Basal ganglia: These structures are found deeper inside the brain. They play a part in control of movement.
Cerebellum: This structure is at the back of the brain. It helps control and coordinate movement, such as walking and balance.
Brainstem: Located just in front of the cerebellum at the juncture of the cerebrum and the spinal cord, the brainstem relays sensory and motor messages between the cerebrum and the rest of the body. This small area is very important and even plays a life-supporting role in functions such as breathing and regulation of your heart rate.
The symptoms caused by a brain metastasis depend on the tumor’s location. For instance, a metastasis in a section of the brain that manages visual processing may cause vision problems.
Though symptoms vary from patient to patient, common brain metastasis symptoms include:
- Headaches: These are often the first symptoms of a brain metastasis. They are caused by the tumor putting pressure on the brain and skull. A headache caused by brain metastases usually becomes progressively worse as time passes. It may not get better with over-the-counter pain medicine and it may be associated with nausea or vomiting. It can get worse when you lie down, bend over or bear down, such as when you have a bowel movement.
- Seizures: Seizures can take many different forms, such as episodes of numbness, tingling, uncontrollable arm and leg movements, difficulty speaking, strange smells or sensations, staring and unresponsive episodes or convulsions.
- Changes in mental function, mood or personality: You may become withdrawn, moody or inefficient at work. You may feel drowsy, confused and unable to think. Depression and anxiety, especially if either develops suddenly, may be an early symptom of a brain tumor. You may become uninhibited or behave in ways you never have before.
- Speech problems: Issues can include trouble finding words, talking incoherently and an inability to express or understand language.
- Changes in the senses: Brain metastases can impact your ability to hear, smell or see. This can include double vision or blurred vision.
- Changes in the sense of touch: Your ability to feel heat, cold, pressure, a light touch or sharp objects may change.
- Loss of balance or coordination.
- Changes in pulse or breathing rates: This symptom is caused by the metastatic tumor pressing against the brainstem.
In addition, brain metastases can harm the brain by:
- Invading and destroying brain tissue.
- Putting pressure on nearby tissue.
- Taking up space and increasing pressure within the skull (intracranial pressure).
- Causing fluid to build-up in the brain.
- Blocking normal circulation of cerebrospinal fluid through the spaces within the brain.
- Causing bleeding in the brain.
If your oncologist suspects a brain metastasis, you will be asked a series of questions about any mental, emotional or physical changes you’ve recently experienced. These questions can help determine if a brain metastasis is the likely cause and give doctors an idea of where the tumor might be located.
You will then undergo a physical exam and an imaging exam, most likely an MRI (magnetic resonance imaging). This exam is the most common way to locate and confirm the diagnosis of a brain metastasis.
If the MRI is inconclusive, doctors may order a biopsy, a procedure in which a piece of the suspected tumor is removed and then tested. Biopsies can be performed surgically (by exposing larger sections of the brain) or with a needle guided by specialized navigation equipment. The location of the growth may make a biopsy difficult, though, and your doctor may recommend no biopsy at all.
In some cases, your physician may find the metastatic disease incidentally. This could happen if you have an imaging exam for something else, and the scan reveals a brain metastasis. When a brain metastasis is found before you begin to notice symptoms, early treatment may be able to prevent the development of neurological symptoms.
Leptomeningeal disease (LMD) is diagnosed differently. In this type of metastases, cancer cells attach to the lining of the brain and spinal cord and float in the liquid surrounding these structures, called cerebrospinal fluid (CSF). Doctors test this fluid to check for LMD. This requires a lumbar puncture (also called a spinal tap). During this procedure, a needle is inserted into the lower back to remove a small amount of CSF from the spinal canal. This sample is then checked for cancer cells. The procedure may be repeated as many as three times to increase the odds of identifying tumor cells.
Your brain metastasis treatment can be planned by a team of experts in neuro-oncology, neurosurgery, radiation oncology and radiology, as well physicians who specialize in the primary cancers most likely to spread to the brain. This group meets every week to review new brain metastasis cases and develop treatment plans designed to give each individual patient the best possible outcome.
Brain metastases surgery
Depending on the number, size, location and symptoms caused by the brain metastasis, surgery may be an option. Surgery is used most often for single, large brain metastases. Like all surgeries, brain metastasis surgery is most successful when it is performed by a specialist with a great deal of experience in the particular procedure. This is especially true with brain metastases because it is crucial to remove as much of the tumor as possible while preserving brain function.
MD Anderson neurosurgeons are among the most skilled and recognized in the world. They perform a large number of brain tumor surgeries each year, using the least-invasive and most advanced techniques.
Even when complete removal of a brain metastasis is not possible, surgery may be able to:
- Help reduce the tumor’s size.
- Relieve symptoms.
- Help doctors determine what other treatments are needed.
The most common surgery for brain tumors is craniotomy, which involves removing a section of the skull to expose the brain, followed by resection (removal) of the tumor. Some brain tumors can be removed with little or no damage to the brain. However, many grow in areas that make them difficult or impossible to remove without destroying important parts of the brain. In these cases, doctors rely on other treatments.
Radiation therapy for brain metastases
Radiation therapy may be able to stop or slow the growth of brain metastases. It may be used alone, as an alternative to surgery, or in combination with other treatments.
New radiation therapy techniques and remarkable skill allow MD Anderson doctors to target brain tumors more precisely, delivering the maximum amount of radiation with the least damage to healthy cells.
MD Anderson uses the most advanced radiation treatment methods, including:
- Gamma Knife stereotactic radiosurgery, which is not really surgery. It delivers a powerful, precise dose of radiation from various angles. This allows doctors to treat the metastasis with minimal damage to surrounding brain tissue.
- Focused radiation therapy, which is aimed directly at the tumor and immediately surrounding area.
- Whole-brain radiation therapy, which may be recommended if you have multiple brain tumors.
- Intensity-modulated radiotherapy (IMRT), which shapes the radiation beam to the shape of the brain tumor and lessens exposure to the rest of the brain.
Radiation therapy may or may not be an effective treatment for your brain metastasis.
Chemotherapy for brain metastases
Chemotherapy was previously not a primary treatment for most brain metastases. This is largely due to the blood-brain barrier, a membrane that separates circulating blood from the brain. This barrier limits many pathogens (such as bacteria and viruses) from spreading to the brain. It also prevents many medications, including most chemotherapy drugs, from reaching the brain.
However, recent research has shown several promising chemotherapies may play an important role in treating some brain metastases.
In some cases, chemotherapy may be used to treat leptomeningeal disease. To administer the chemotherapy, doctors must first drill a small hole in the skull and insert a special port, called an Ommaya reservoir. This allows doctors to deliver the drug directly into the cerebrospinal fluid. This technique, called intrathecal chemotherapy, can only penetrate a few millimeters into the leptomeninges. If the tumor is any thicker, doctors may first try to shrink the growth with radiation.
Laser interstitial thermal therapy
Laser interstitial thermal therapy (LITT) is performed by inserting a laser probe into the tumor and heating it to temperatures high enough to destroy it. The treatment is minimally invasive. It only requires a small incision. This makes LITT an option for metastases that can’t be removed with surgery due to their location. Most patients who undergo LITT can go home the day after treatment and quickly return to normal activities.
Immunotherapy for brain metastases
Immunotherapy uses the body’s own immune system to fight cancer. These treatments are relatively new and are proving effective in treating melanoma brain metastases, but are still being studied in other metastatic tumor types.
Targeted therapy for brain metastases
Targeted therapies target the specific gene mutations that cause cancer. Several of these drugs are under investigation in clinical trials for patients with specific types of cancer.
Why choose MD Anderson for your brain metastasis treatment?
When a patient is diagnosed with a brain metastasis, treating that growth becomes a top priority. At MD Anderson, your case can be reviewed by our central nervous system metastases tumor board. This group includes physicians who specialize in primary cancers (the tumors that spread to the brain) as well as experts in neurosurgery, neuro-oncology, radiology and radiation oncology for the central nervous system.
Members of this team have spent decades treating patients with brain metastases. They often find ways to treat tumors that other care providers have declared untreatable. This combination of experience and expertise helps them deliver a personalized treatment plan offering the best possible outcome.
As a patient at a top-ranked cancer center, you will also benefit from advanced imaging techniques that can identify and track your brain metastasis over time. Your care may include some of the most advanced surgeries and therapies available. These include complex procedures many providers do not offer, such as awake craniotomies, which allow doctors to map the brain during surgery to avoid damaging vital spots.
You can also benefit from advanced treatments such as Gamma Knife® stereotactic radiosurgery, stereotactic radiosurgery to the spinal cord, image-guided radiation therapy and laser interstitial thermal therapy (LITT). These treatments allow precise treatment of metastases while minimizing the effects on nearby healthy tissue. Doctors might also offer you the opportunity to participate in clinical trials that may not be available anywhere else.
And since brain metastases and their treatments can impact how you think and behave, we have experts who can evaluate symptoms related to your disease and help find ways to minimize those effects.
Usually going to a hospital is a bad feeling, but for me coming back to MD Anderson is a great feeling. It’s a feeling of security, that I’m getting the correct treatment.
Brain metastasis survivor
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