Oligodendroglioma

What is oligodendroglioma?

Oligodendroglioma is a type of brain tumor, but in rare cases, it can form in your spinal cord. These tumors develop from a specific type of glial cell: oligodendrocytes. Glial cells are the support cells of your nervous system. They maintain and protect the neurons that send and relay signals within, to and from your brain.

Tumors that come from glial cells are called gliomas. Oligodendrogliomas account for between 5% and 15% of all gliomas, and about 3% to 4% of all brain tumors. Worldwide, healthcare providers diagnose just under 24,000 people with oligodendroglioma each year. Most people who have it are between the ages of 40 and 50.

What are oligodendrocytes?

The name “oligodendrocyte” comes from several Greek words and breaks down like so:

• Oligo-: Small.
• -dendro-: Tree-like.
• -cytes: Cells.

Every neuron has a main cell body with an arm-like extension called an axon. Many neurons have a myelin sheath around their axon. This fatty coating protects the axon and maintains signal speed as it passes through the neuron.

Oligodendrocytes have a main body and dozens of arm-like extensions that wrap around the axons of about 30 to 40 nearby neurons (which is why oligodendrocytes are “tree-like”). These extensions provide the myelin sheath for the axons of the connected neurons.

Are there different types of oligodendrogliomas?

The World Health Organization (WHO) grading scale ranges from grade 1 (lowest) to grade 4 (highest). Oligodendrogliomas fall into two main types under this grading scale:

• Oligodendrogliomas WHO grade 2: Also known as “low-grade oligodendrogliomas,” these oligodendrogliomas typically grow slowly. They also tend to respond well to treatment.
• Oligodendrogliomas WHO grade 3: Also known as “high-grade oligodendrogliomas” (and formerly known as “anaplastic oligodendrogliomas”), these are malignant. That’s because they’re more aggressive. They may spread faster and be harder to treat.

What are the symptoms of oligodendroglioma?

Like many brain cancers, oligodendrogliomas often don’t cause symptoms until they disturb brain tissue around them. The most common symptoms are headaches or seizures. Up to 80% of people with oligodendroglioma will have a seizure because of this cancer. That’s because oligodendrogliomas commonly affect your cerebral cortex, the wrinkly outer surface of your brain. The cortex is home to brain areas that control many of the abilities you use in everyday life, like vision, language, muscle control and more.

Besides seizures, oligodendrogliomas may cause focal symptoms. These symptoms indicate a problem that’s focused (hence the name “focal”) in a specific area of your brain. They usually affect a body part or an ability. Examples of focal symptoms can include:

• Muscle weakness or paralysis, especially on one side of your body or face.
• Hearing loss.
• Trouble speaking or understanding others who are talking (aphasia).
• Vision loss, double vision or blurred vision.
• Memory problems.
• Trouble thinking or concentrating.

What causes oligodendroglioma?

By definition, all oligodendrogliomas happen because of two specific DNA changes:

• 1p/19q co-deletion: Chromosomes are the compressed DNA “data” your cells use as an instruction manual. Sometimes, errors happen when chromosomes are copied as your cells reproduce. Oligodendrogliomas always have deletions on the short (p) arm of chromosome 1 and the long (q) arm of chromosome 19. Experts often refer to this as a “1p/19q co-deletion.”
• IDH1 or IDH2 mutation: Genes are sections of the data in your DNA that contain specific instructions. One of these tells your body how to make an enzyme called isocitrate dehydrogenase (IDH), which helps with certain types of metabolism. Two IDH mutations, IDH1 or IDH2, can cause oligodendrogliomas.

The above genetic changes are all “de novo,” which means “new.” That means these mutations and deletions happen spontaneously. You don’t inherit them from either of your biological parents.

What are the risk factors for oligodendroglioma?

Researchers haven’t confirmed any risk factors for oligodendroglioma. But there’s research that could mean past radiation therapy (like the type used to treat other cancers) is a possible factor for developing similar tumors called gliomas. More research is necessary to confirm if that could be a cause or contributing factor.

What are the complications of oligodendroglioma?

Oligodendrogliomas affect your brain, so they can cause many possible complications. The complications you could experience depend on many factors, especially the location of the oligodendroglioma, other health conditions you have and more.

Some complications to be aware of include:

• Malignant transformation: Low-grade oligodendrogliomas that aren’t cancer can sometimes “transform.” That means the cells in the tumor change over time and become cancerous.
• Strokes or similar circulatory-related problems: Oligodendroglioma growing inside your skull or brain will take up more and more space, displacing the brain tissue around it. That can lead to strokes or stroke-like events.
• Skull structure changes: Oligodendrogliomas are often calcified, meaning they harden because calcium accumulates in them. When that happens on the outside of your brain, it can start to affect the bone of your skull. Slow-growing oligodendroglioma may cause surrounding bone tissue to shift or change, too.

How is oligodendroglioma diagnosed?

A healthcare provider will diagnose oligodendroglioma using multiple methods, including:

• A physical and neurological exam.
• Diagnostic imaging.
• A brain biopsy and pathology testing.

Diagnostic imaging is especially important with oligodendrogliomas because it lets providers “see” inside your head. The scans that are most likely to help are:

• Computed tomography (CT) scans: These are often the first imaging scan after a person has a seizure or any focal symptoms. Your bones contain calcium, so they’re bright on X-rays and CT scans. Oligodendrogliomas also often contain calcium, so they also often show up brightly.
• Magnetic resonance imaging (MRI) scans: These scans can clearly display the different structures inside your head. They can help determine the size of an oligodendroglioma and its precise location.

But imaging scans alone aren’t enough to diagnose an oligodendroglioma. They only provide evidence that you have a tumor in your brain that might be an oligodendroglioma. That evidence is what providers use to determine if you need a brain biopsy and pathology testing.

A brain biopsy is a surgical procedure where a neurosurgeon will collect a tiny tumor sample. The tumor sample then goes to a lab for analysis. The analysis will look at the cells under a microscope for visible changes. The sample will also undergo genetic/molecular testing to determine if you have a 1p/19q chromosome co-deletion and an IDH mutation. If testing finds both, a healthcare provider can diagnose the tumor as an oligodendroglioma.

Depending on your symptoms, medical history and any other health concerns, there are other tests you might need to undergo. Your healthcare provider can recommend these tests and explain why they may help.

How is oligodendroglioma treated, and is there a cure?

Oligodendrogliomas are among the more treatable brain tumors and cancers. The treatment often involves multiple methods, including:

• Surgery.
• Chemotherapy.
• Radiation therapy.

Surgery

Brain surgery aims to remove as much of the tumor as possible. Sometimes, a neurosurgeon can remove the whole tumor. The success rate of surgery depends strongly on the type of oligodendroglioma, how much it’s progressed, the tumor’s location, your surgeon’s expertise and other factors.

Depending on surgery outcomes, the amount of tumor your surgeon is able to remove, the tumor grade, your age and your general health, you may or may not need radiation therapy and/or chemotherapy. Your care team will explain all the options for you based on the National Comprehensive Cancer Network (NCCN) guidelines.

Chemotherapy

Certain chemotherapy drugs are very effective against oligodendroglioma. The most likely chemotherapy treatments are:

• The PCV regimen: The name of this regimen comes from the three drugs it consists of: procarbazine, lomustine (often known by its chemical abbreviation “CCNU,” making it the “C” in PCV) and vincristine. PCV is generally the first option for treating oligodendroglioma.
• Temozolomide: Healthcare providers sometimes recommend this drug instead of the PCV regimen. The side effects of temozolomide are usually not as severe as those possible with the PCV regimen, and research shows its effectiveness is very similar to PCV.

Radiation therapy

Radiation therapy is very common with oligodendroglioma. This approach bombards tumor cells with enough energy to destroy them. The radiation is targeted as precisely as possible. The goal is to destroy as much of a tumor as possible while leaving surrounding healthy tissue unharmed.

Complications/side effects of the treatment

The side effects or complications of oligodendroglioma treatments depend strongly on the treatments themselves and other factors. Your healthcare provider is the best person to tell you more about the side effects or complications that are most likely in your case and what you can do about them.

Can I lower my risk of developing oligodendroglioma or prevent it entirely?

Experts don’t know why oligodendrogliomas happen or what makes them more likely to occur. Because of that, there’s no way to prevent it or reduce your risk of having it.

What can I expect if I have oligodendroglioma?

Oligodendroglioma is a type of brain tumor, so it’s a serious concern. But it’s more treatable and less dangerous than other types of gliomas.

Most people won’t know they have oligodendroglioma until they have symptoms, especially seizures or headaches. A first-time seizure is always something that needs emergency medical care. Headaches need medical attention when they’re frequent, happen with certain activities or occur in a way that disrupts your life.

Having symptoms is usually what leads to an imaging test that first detects an oligodendroglioma. Once detected, a healthcare provider will recommend testing to diagnose what you have and determine how to treat it. Treating oligodendroglioma is important because even low-grade, benign tumors can eventually turn into cancer. Limiting the spread of oligodendroglioma is a key way to prevent further complications or spreading to other parts of your body.

What’s the outlook for oligodendroglioma?

An oligodendroglioma is serious, but the outlook tends to be positive. The five-year survival rates (the percentage of people who are alive five years after diagnosis) for low-grade oligodendrogliomas range from 69% to 90%. Younger adults have a higher five-year survival rate. The five-year survival rates for high-grade oligodendroglioma are 45% to 76%.

There’s also a new drug that researchers are working on that shows promise for oligodendrogliomas with IDH mutations. This drug is still in development, but the early data indicates that it could increase the odds of a better outcome.

How do I take care of myself?

If you have oligodendroglioma, your healthcare provider will help you decide which treatment approach is best for you. They’ll also recommend a treatment schedule and regular follow-up visits.

Going to your treatments and follow-up visits is very important. Receiving treatment consistently and as recommended is also vital.

Side effects are common with many of the treatments for oligodendroglioma. Your healthcare provider can help you understand the possible side effects that are most likely to affect you and what you can do about them.

What questions should I ask my doctor?

You may want to ask your healthcare provider any of the following:

• What grade is my oligodendroglioma?
• Where is it, and what abilities might it affect?
• What are the treatment options?
• Is it possible to remove all of the tumor with surgery?
• What are the possible complications or side effects of treatment?
• Do you recommend chemotherapy, radiation therapy or both?
• What’s the treatment timeline?
• During and after treatment, what symptoms mean I need immediate medical attention?

Is oligodendroglioma cancer curable?

Oligodendrogliomas are treatable, but not technically “curable,” tumors. The most likely approach to treating oligodendroglioma is to remove the whole tumor (or as much of it as possible) and then your care team determines if chemotherapy, radiation therapy or a combination of these are necessary to eradicate any remaining cancer cells.

Is oligodendroglioma fatal?

Like all tumors or cancers, oligodendroglioma can be fatal. But oligodendroglioma generally has higher survival rates than other gliomas and brain cancers. The chances of prolonged survival are higher with lower-grade tumors. Other factors can also play a role, so your healthcare provider can tell you more about the outlook for your specific case.

A note from Cleveland Clinic

Hearing that you have any kind of tumor can be a life-changing moment. You might experience fear, shock or anger. But having oligodendroglioma doesn’t mean the situation is hopeless. In fact, oligodendroglioma has higher survival rates than most brain tumors, especially when it’s a lower-grade tumor.

Oligodendroglioma generally responds well to multiple forms of treatment, and most people with it will survive for many years. Better still, advances in treatment options offer the chance for higher survival odds and quality of life for people with oligodendroglioma.