A brain tumor is an abnormal growth or mass of cells in or around your brain. Together, spinal tumors and brain tumors are called central nervous system (CNS) tumors.
Brain tumors can be malignant (cancerous) or benign (noncancerous). Some tumors grow quickly, while others are slow growing.
Only about one-third of brain tumors are cancerous. But whether they’re cancerous or not, brain tumors can impact brain function and your health if they grow large enough to press on surrounding nerves, blood vessels, and tissue.
Tumors that develop in your brain are called primary tumors. Tumors that spread to your brain after forming in a different part of your body are called secondary tumors or metastatic brain tumors. This article focuses on primary brain tumors.
What are the types of brain tumors?
Researchers have identified more than 150 different brain tumors.
Healthcare providers categorize primary tumors as glial (composed of glial cells in your brain) or non-glial (developed on or in the structures of your brain, including nerves, blood vessels, and glands), and benign (noncancerous), malignant (cancerous).
Many types of brain tumors can also form in your spinal cord or column.
Usually, benign brain tumors
Types of brain tumors that are usually benign include:
- Chordomas: These slow-growing tumors typically begin at the base of your skull and the bottom part of your spine. They’re mostly benign.
- Craniopharyngiomas: These tumors usually arise from a portion of your pituitary gland. They’re difficult tumors to remove because of their location near critical structures deep in your brain.
- Gangliocytomas, gangliomas, and anaplastic gangliogliomas: These are rare tumors that form in neurons (nerve cells).
- Glomus jugular: These tumors are typically located just under the base of your skull at the top of your jugular vein (neck vein). They’re the most common form of glomus tumor.
- Meningiomas: These are the most common type of primary brain tumors. Meningiomas typically develop slowly. They form in the meninges, the layers of tissue that protect your brain and spinal cord. In rare cases, a meningioma can be malignant.
- Pineocytomas: These slow-growing tumors form in your pineal gland, which is located deep in your brain and secretes the hormone melatonin.
- Pituitary adenomas: These tumors form in your pituitary gland, which is located at the base of your brain. Your pituitary gland makes and controls hormones in your body. Pituitary adenomas are usually slow growing, and they may release excess pituitary hormones.
- Schwannomas: These are common benign brain tumors in adults. They develop from the Schwann cells in your peripheral nervous system or cranial nerves. Schwann cells assist in the conduction of nerve impulses. Acoustic neuromas are the most common schwannoma. These tumors occur on your vestibular nerve (the nerve that leads from your inner ear to your brain).
Cancerous (malignant) brain tumors
Approximately 78% of cancerous primary brain tumors are gliomas. These tumors develop in glial cells, which surround and assist nerve cells.
Types of gliomas include:
- Astrocytoma: These tumors are the most common type of glioma. They form in the star-shaped glial cells called astrocytes. They can form in many parts of your brain but most commonly occur in your cerebrum.
- Ependymomas: These tumors often occur near the ventricles in your brain. Ependymomas develop from ependymal cells (called radial glial cells).
- Glioblastoma (GBM): These tumors form in glial cells called astrocytes. GBMs are the fastest-growing astrocytoma.
- Oligodendroglioma: These uncommon tumors begin in cells that create myelin (a layer of insulation around nerves in your brain).
Medulloblastoma is another type of cancerous brain tumor. These tumors are fast-growing and form at the base of your skull. They’re the most common cancerous brain tumor in children.
What causes brain tumors?
Researchers know brain tumors develop when certain genes on the chromosomes of a cell are damaged and no longer function properly, but they aren’t sure why this happens. The DNA in your chromosomes tells cells throughout your body what to do — it tells them when to grow when to divide or multiply, and/or when to die.
When brain cell DNA changes, it gives your brain cells new instructions. Your body develops abnormal brain cells that grow and multiply faster than normal and sometimes live longer than normal. When that happens, the ever-growing crowd of abnormal cells takes over space in your brain.
In some cases, a person may be born with changes in one or more of these genes. Environmental factors, such as exposure to large amounts of radiation from X-rays or previous cancer treatment, may then lead to further damage.
In other cases, the environmental injury to the genes may be the only cause.
There are a few rare, inherited (passed down from parent to child) genetic syndromes that are associated with brain tumors, including:
- Neurofibromatosis type 1 (NF1 gene).
- Neurofibromatosis type 2 (NF2 gene).
- Turcot syndrome (APC gene).
- Gorlin syndrome (PTCH gene).
- Tuberous sclerosis complex (TSC1 and TSC2 genes).
- Li-Fraumeni syndrome (TP53 gene).
- Only about 5% to 10% of people with brain tumors have a family history of a brain tumor.
How are brain tumors diagnosed?
Diagnosing a brain tumor can be a complicated process and may involve several specialists. In some cases, though, healthcare providers may discover a brain tumor when performing imaging tests for another medical issue. If you’re experiencing symptoms of a brain tumor, your healthcare provider will perform a physical exam. They’ll also ask questions about your:
- Past and current health conditions.
- Current medications.
- Surgeries and medical treatments.
- Family medical history.
They may also perform a neurological exam, which involves looking for changes in your:
- Balance and coordination.
- Mental status.
These changes can point to the part of your brain that may be affected by a tumor.
If your healthcare provider suspects you may have a brain tumor, a brain scan, most often an MRI, is usually the next step.
What tests will be done to diagnose a brain tumor?
Healthcare providers use several tests to diagnose a brain tumor, including:
Brain MRI or CT scan: Magnetic resonance imaging (MRI) is the best imaging test for identifying brain tumors. Computed tomography (CT) is a good alternative if you’re unable to undergo an MRI. Before these tests, a substance that makes the tumor easier to see, called a contrast agent, is injected into one of your veins. These tests can show the tumor’s size and exact position in specific detail. Your healthcare provider may also look at other parts of your body, such as your lungs, colon, or breasts, to see if the tumor has spread.
Biopsy: Healthcare providers usually need to do a biopsy of the tumor (removal of a sample of the tumor for examination under a microscope) to identify the type of tumor and if it’s cancerous. A neurosurgeon may perform a biopsy during surgery in which they remove all or part of the tumor. If the tumor is difficult to reach, they may perform a stereotactic biopsy, which involves creating a small hole in your skull and using a needle to take a sample of tissue from the tumor.
Spinal tap (lumbar puncture): For this procedure, your healthcare provider uses a small needle to remove cerebrospinal fluid (CSF) from around your spine. A laboratory examines this fluid to look for cancer cells. Healthcare providers use this procedure when they suspect that the tumor has invaded the layers of tissues that cover your brain (meninges).
Specialized tests: Certain tests can sometimes help with the diagnosis. For example, your healthcare provider may order tests that check your blood and cerebrospinal fluid for substances that certain tumors release, called tumor markers. They can also test for gene abnormalities that are characteristic of certain tumors.
How are brain tumors treated?
Brain tumor treatment depends on several factors, including:
- The tumor’s location, size, and type.
- The number of tumors.
- Your age.
- Your overall health.
Benign (noncancerous) brain tumors can usually be successfully removed with surgery and don’t usually grow back. It often depends on if your neurosurgeon can safely remove all of the tumors.
Treatments that are fairly well tolerated by the brains of adults, such as radiation therapy, may prevent the normal development of a child’s brain, especially in children younger than age five.
Healthcare providers often use a combination of therapies to treat a tumor.
Your treatment options might include the following:
Brain surgery (craniotomy): When possible, neurosurgeons remove the tumor. They work very carefully, sometimes performing surgery when you’re awake (you won’t feel pain) to minimize damage to functional areas of your brain.
Radiation therapy: High doses of X-rays destroy brain tumor cells or shrink the tumor in this type of treatment.
Radiosurgery: This is a type of radiation therapy that uses very focused beams of radiation (gamma rays or proton beams) to destroy a tumor. It’s not actually surgery because it doesn’t require an incision (cut).
Brachytherapy: This is a form of radiation therapy. It involves surgically placing radioactive seeds, capsules, or other implants directly in or near the cancerous tumor.
Chemotherapy: This therapy consists of anticancer drugs that kill cancer cells in your brain and throughout your body. You might receive chemotherapy through an injection into a vein or take it as a pill. Your healthcare provider may recommend chemotherapy after surgery to kill any cancer cells left behind or to prevent remaining tumor cells from growing.
Immunotherapy: Immunotherapy, also called biological therapy, is a type of treatment that uses your body’s immune system to fight cancer. The therapy mainly consists of stimulating your immune system to help it do its job more effectively.
Targeted therapy: With this treatment, drugs target specific features in cancer cells without harming healthy cells. Your healthcare provider may recommend targeted therapy if you have trouble tolerating the side effects of chemotherapy, such as fatigue and nausea.
Watchful waiting/active surveillance: If you have a brain tumor that’s very small and isn’t causing symptoms, your healthcare provider may recommend closely monitoring the tumor for signs of growth with regular testing.
Other treatments that help with symptoms caused by brain tumors include:
Shunts: If the tumor causes pressure within your skull to increase, you may need to have a shunt (a thin piece of tubing) surgically placed in your brain to drain excess cerebrospinal fluid.
Drugs such as mannitol and corticosteroids: These medications can help reduce pressure within your skull. They reduce swelling around the tumor.
Palliative care: This is a specialized form of care that provides symptom relief, comfort, and support to people living with serious illnesses. It also provides support to caregivers and those impacted by a loved one’s condition.
Can brain tumors be prevented?
Unfortunately, you can’t prevent a brain tumor. You can reduce your risk of developing a brain tumor by avoiding environmental hazards such as smoking and excessive radiation exposure. If you have a first-degree biological relative (sibling or parent) who has been diagnosed with a brain tumor, it’s important to tell your healthcare provider. They may recommend genetic counseling to see if you have an inherited genetic syndrome that’s associated with brain tumors.