Glioma brain tumors (astrocytoma, oligodendroglioma, glioblastoma)

Overview

A glioma is a tumor of the glial cells in the brain and spinal cord. Gliomas can range from benign and slow-growing to the most aggressive and malignant brain tumors. Glioma types include astrocytoma, oligodendroglioma, ependymoma, and glioblastoma. Gliomas may be low-grade or high-grade based on the cell type, gene mutations, and how quickly they grow.

This fact sheet provides an overview of glioma. See Brain Tumors: An Introduction for more information.

What is a glioma?

A glioma is a primary brain tumor, meaning it grows from the brain tissue itself. Glial cells support neurons with energy and maintain the blood-brain barrier. Each type of glial cell has a different role:

Astrocyte - transports nutrients and holds neurons in place
Oligodendrocyte - provides insulation (myelin) for neurons
Ependymal cells - line the ventricles and secrete cerebrospinal fluid

Glioma is an umbrella term used to describe the types of glial tumors: astrocytoma, glioblastoma, oligodendroglioma, and ependymoma. Gliomas vary in their aggressiveness or malignancy. Some are slow-growing and likely to be curable. Others are fast-growing, invasive, difficult to treat, and likely to recur.

What are the symptoms?

Symptoms of gliomas depend on their location in the brain. Common signs include headaches, seizures, nausea, numbness or weakness on one side of the body, personality or cognitive changes, or aphasia.

How is a diagnosis made?

If you have symptoms that suggest a glioma, a team of specialists will work to confirm the diagnosis. Your team may include a neurosurgeon, oncologist, radiation oncologist, radiologist, neurologist, and pathologist.

The doctor will ask about your medical history and symptoms, and perform a neurological exam. MRI and CT imaging scans can detect a brain tumor and determine its size, location, and invasiveness.

A biopsy may be performed if a diagnosis is not clear from the MRI. A sample of tumor cells can be taken during surgery, either to remove the tumor or as a separate diagnostic procedure. Biopsies can be needle biopsies or open.

A pathologist views the biopsy tumor cells under a microscope to classify the glioma type, followed by cell analysis and gene biomarker tests. The proliferative index measures the percentage of tumor cells that are actively dividing and growing. Molecular profiling reveals DNA mutations that help predict tumor behavior and prognosis. These include: IDH1, IDH2, ATRX, 1p/19q codeletion, EGFR, MGMT, and TERT. On average, patients who have IDH, MGMT, and 1p/19q mutations have a better prognosis.

 

How are gliomas treated?

Treatment options vary depending on the tumor cell type, grade, size, and location. The goal of treatment may be curative, or it may focus on relieving symptoms (palliative care). Treatments are often used in combination with one another.

Gliomas are graded by the cell activity and aggressiveness, with grades ranging from 1 to 4.

 

LOW-GRADE GLIOMAS 1 and 2

Grade 1 – Pilocytic astrocytoma: typically occurs in children in the cerebellum or near the brainstem. Grade 1 gliomas are slow-growing and relatively benign. Treatment options include:

• Observation –small tumors and tumors located in inoperable areas (brainstem) may be monitored with MRI and may never grow.
• Surgery – treatment of choice in most cases. Complete removal can be curative.
• Radiation – reserved for inoperable tumors, residual tumor after surgery, or recurrence.

Grade 2 – Low-grade glioma: includes diffuse astrocytoma (IDH mutant), and oligodendroglioma (IDH mutant, 1p/19q codeleted). Grade 2 gliomas typically occur in adults and are most often found in the cerebrum. Due to the infiltrative nature of these tumors, recurrences are likely to occur. Some grade 2 gliomas recur and evolve into more aggressive tumors (grade 3 or 4). Treatment options include:

• Observation – for tumors located in inoperable or high-risk areas that may cause loss of function after surgery. Some tumors may never grow, but others will enlarge or transform to a high-grade tumor warranting treatment.
• Surgery – treatment of choice if the tumor can be removed without causing loss of function. Complete removal can be curative.
• Vorasidenib (Voranigo) – IDH inhibitor drug that can delay tumor progression. IDH1/2 mutations occur in 80% of grade 2 gliomas.
• Radiation (fractionated) – can be used after surgery to slow residual tumor growth or in cases where surgery is not an option.
• Chemotherapy – temozolomide or PCV can be given alone or in combination with radiation.

HIGH-GRADE GLIOMAS 3 and 4

Grade 3 – Malignant glioma: includes anaplastic astrocytoma and anaplastic oligodendroglioma. Grade 3 tumors grow faster and more aggressively than grade 2. They invade nearby brain tissue with tentacle-like projections, making complete surgical removal more difficult. Patients often present with seizures, neurologic deficits, headaches, or changes in mental status.

 

Grade 4 – Glioblastoma (GBM): is a malignant glioma. GBM (IDH wildtype) is the most aggressive and most common primary brain tumor. Glioblastoma spreads quickly and invades other parts of the brain, with tentacle-like projections, making complete surgical removal difficult. It is common for GBMs to recur after initial treatment.

Treatment for high-grade 3 and 4 gliomas include:

• Observation – not typically an option due to malignancy and rapid growth.
• Surgery – maximal resection of the tumor is recommended if the tumor can be removed without causing loss of function.
• Radiation (fractionated) – is given after surgery every weekday for a duration of 6 weeks.
• Chemotherapy – temozolomide is given during and after radiation for 6-12 months.
• Tumor-treating fields (Optune) – a bathing cap device emits electrical energy. It slows tumor growth by keeping cells from dividing.

A follow-up MRI scan is done 3 weeks after completion of radiation and chemotherapy. It is used to monitor the tumor for any changes or growth since the start of therapy.

Recurrence of grade 3 or 4 gliomas common. It typically occurs at the site of the initial tumor, usually within 2 cm. Treatment of recurrences can include:

• Additional surgery, radiation, or chemotherapy.
• Radiation seeds (GammaTile) – tiles are placed in the tumor cavity at the time of surgery. They deliver a continuous radiation dose to the tumor margin where recurrence is likely. Currently, these are used at the time of tumor recurrence.
• Stereotactic radiosurgery – generally used in conjunction with chemotherapy or Avastin.
• Bevacizumab (Avastin) – a VEGF inhibitor drug that blocks tumor blood vessel growth in recurrent glioma.
• Clinical trials – based on the molecular profile of the tumor, patients may be eligible to enroll in a trial and receive an investigational therapy.

Treatment Glossary

Medications to control side effects of brain tumors:

• Steroids, such as dexamethasone (Decadron), reduce swelling and fluid build-up (edema) around the tumor. Because steroids can cause stomach ulcers and reflux, famotidine (Pepcid) or pantoprazole (Protonix) are prescribed to reduce the acid.
• Mannitol (Osmitrol) controls edema and swelling.
• Anticonvulsants prevent or control seizures. Common ones include levetiracetam (Keppra), carbamazepine (Tegretol), and valproic acid (Depakote).

Surgery: A craniotomy is performed to open the skull and remove a tumor. The surgeon may remove only part of the tumor if it is near critical (eloquent) areas of the brain. Image-guidance, 5-ALA tumor fluorescence, brain mapping, and awake surgery are techniques that help the surgeon identify the tumor margins for maximal removal and avoid vital brain areas (e.g., speech). A partial removal can still relieve symptoms and provide a survival benefit. Radiation or chemotherapy may be used on the remaining tumor cells.

Radiation therapy: High-energy rays damage the DNA inside cells, making them unable to divide and reproduce. The goal of radiation is to maximize the dose to tumor cells and minimize exposure to normal cells. Ways to deliver radiation include:

• Fractionated stereotactic radiotherapy: delivers lower doses of radiation over many visits. A facemask accurately positions the head for each treatment session. Patients return weekdays over 5-6 weeks to receive the complete radiation dose.
• Proton therapy: a form of fractionated radiotherapy that delivers a high-energy beam of protons to a specific depth in the tumor.
• Radiation seeds (GammaTile): deliver a continuous low dose of radiation from inside the tumor. After tumor surgery, collagen tiles containing 4 radiation seeds are placed inside the cavity. The radiation dose affects the first few millimeters of the tumor cavity where malignant cells remain.
• Stereotactic radiosurgery (SRS): delivers a high dose of radiation during a single session, or 5 daily sessions. Because of the high dose, the head is immobilized with a stereotactic frame or facemask. Patients spend the day at the center while the tumor is precisely located, a treatment plan is developed, and a radiation dose is delivered.

Chemotherapy: Drugs work by interrupting cell division. Chemotherapy affects not only tumor cells but also normal dividing cells. This causes side effects (e.g., hair loss, fatigue, low blood count). Chemotherapy can be taken as a pill, intravenously (IV), or as a wafer placed into the tumor. Drugs commonly used to treat gliomas are temozolomide (Temodar) and PCV (procarbazine, lomustine, and vincristine). Treatment is given in cycles, with rest periods in between to allow the body to rebuild healthy cells.

• Chemotherapy wafers: are placed in the tumor cavity after surgery. They are the size of a nickel and made of a polymer that has been filled with carmustine (BCNU).

Targeted therapy: Biologics that slow or block activity of specific gene mutations in gliomas.

• Bevacizumab (Avastin): a VEGF inhibitor drug that prevents new tumor-feeding blood vessels from developing. It works by starving the tumor of food and oxygen. It is an infusion given every 2 weeks for recurrent glioma.
• Vorasidenib (Voranigo): delays tumor progression by blocking mutated IDH1 and IDH2 enzymes. It is a pill approved for low grade IDH-mutant gliomas.

Tumor Treating Fields (Optune): slows and reverses tumor growth by keeping cells from dividing. TTFields is used to treat newly-diagnosed glioblastoma (GBM) in combination with temozolomide. It is also approved for recurrent GBM. Treatment involves wearing sticky pads attached to the scalp that are wired to a portable battery. The array pads deliver alternating electric energy to the tumor cells. It is worn 18 hours a day and requires your hair to be shaved.

Laser interstitial thermal therapy (LITT): uses heat to destroy tumor cells. It is a minimally invasive alternative to an open craniotomy. A LITT probe is inserted through a small burr hole in the skull. Once the tip of the probe is positioned in the tumor using MRI guidance, a laser beam is directed through the probe to heat up the tip and damage the abnormal cells. The procedure takes place in an MRI room.

 

Clinical trials

Clinical trials are research studies in which new treatments—drugs, diagnostics, procedures, and other therapies—are tested in people to see if they are safe and effective. Research is always being conducted to improve the standard of medical care. Information about current clinical trials is online at clinicaltrials.gov and centerwatch.com.

• Immunotherapy activates the immune system (T-cells and antibodies) to destroy tumor cells. One avenue of research in this area is exploring ways to prevent or treat cancer through vaccines.
• Gene therapy uses viruses or other vectors to introduce new genetic material into tumor cells. This experimental therapy can cause tumor cells to die or increase their susceptibility to other cancer therapies.

Recovery

Your primary care doctor and oncologist should discuss any home care needs with you and your family. Supportive measures vary according to your symptoms. For example, canes or walkers can help those having trouble walking. A plan of care to address changes in mental status should be adapted to each patient's needs.

Driving privileges may be suspended while you are taking anti-seizure medication. This is for your safety and the safety of others. As each state has different rules about driving and seizures, discuss this issue with your doctor.

Discuss advance medical directives with your family. A living will, health care proxy, and durable power of attorney outline your wishes for medical care if you are unable to express them yourself.

Recurrence

How well a tumor will respond to treatment, remain in remission, or recur depends on the tumor type and its molecular makeup. A recurrent tumor may be a tumor that persists after treatment, one that grows back some time after treatment has destroyed it, or a new tumor that grows in the same place as the original one.

When a brain tumor is in remission, the tumor cells have stopped growing or multiplying. Periods of remission vary. In general, benign tumors recur less often than malignant ones.

Since it is impossible to predict whether or when a particular tumor may recur, monitoring with MRI or CT scans is essential for people treated for glioma. Follow-up scans are performed every 3 to 6 months or annually, depending on your tumor type.

Sources & links

If you have more questions, please contact Mayfield Brain & Spine at 800-325-7787 or 513-221-1100.

Support groups provide an opportunity for patients and their families to share experiences, receive support, and learn about advances in treatments.

Links

National Brain Tumor Society
American Brain Tumor Association

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updated > 1.2025
reviewed by > Yair Gozal, MD, PhD, Ronald Warnick, MD, Mayfield Clinic, Cincinnati, Ohio