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Oligodendroglioma and Other IDH-Mutated Tumors: Diagnosis and Treatment

MRI of an oligodendroglioma in the brain.

Credit: NCI-CONNECT Staff

Oligodendroglioma is a primary central nervous system (CNS) tumor. This means it begins in the brain or spinal cord. Diagnosing oligodendroglioma requires finding two genetic alterations: an IDH mutation and a very specific change in the tumor cell’s chromosomes where the short arm of chromosome 1 and the long arm of chromosome 19 is lost (also known as 1p19q codeletion). Content on other IDH-mutated tumors will be coming soon.

To get an accurate diagnosis, a piece of tumor tissue will be removed during surgery, if possible. A neuropathologist should then review the tumor tissue.

What are the grades of oligodendrogliomas?

Primary CNS tumors are graded based on the tumor location, tumor type, extent of tumor spread, genetic findings, the patient’s age, and tumor remaining after surgery, if surgery is possible.

Oligodendrogliomas are grouped in two grades (grade 2 or grade 3, also written as grade II or grade III) based on their characteristics.

  1. Grade 2 oligodendrogliomas are low grade tumors. This means the tumor cells grow slowly and invade nearby normal tissue. In many cases, they form years before being diagnosed as no symptoms appear.
  2. Grade 3 oligodendrogliomas are malignant (cancerous). This means they are fast-growing tumors. They are called anaplastic oligodendriogliomas.

What do oligodendrogliomas look like on an MRI?

Oligodendrogliomas usually appear as a single tumor with well-defined borders. The tumor may enhance with contrast and is most often seen in anaplastic oligodendrogliomas. Oligodendrogliomas tend to have some swelling around them.

What causes oligodendrogliomas?

Cancer is a genetic disease – that is, cancer is caused by certain changes to genes that control the way our cells function. Genes may be mutated (changed) in many types of cancer, which can increase the growth and spread of cancer cells. The cause of most oligodendrogliomas is not known. Exposure to radiation and certain gene changes that can be passed down through families have been linked to a higher chance of developing oligodendrogliomas.

Where do oligodendrogliomas form?

Oligodendrogliomas are commonly found in the white matter and the outer layer of the brain, called the cortex, but can form anywhere in the CNS. These tumors are called oligodendrogliomas because the cells resemble oligodendrocytes, a type of brain cell that supports and insulates nerve fibers in the CNS.

Do oligodendrogliomas spread?

Oligodendrogliomas can spread to other areas of the CNS through cerebrospinal fluid (CSF), but is uncommon. Oligodendrogliomas rarely spread outside of the CNS to other organs.

What are the symptoms of an oligodendroglioma?

Symptoms related to oligodendrogliomas depend on the tumor’s location. Here are some possible symptoms that can occur.

Oligodendroglioma Symptoms

The most common sign of an oligodendroglioma is a seizure. Around 60% of people have a seizure before being diagnosed.

Other symptoms people may have:

  • Headaches
  • Problems with thinking and memory
  • Weakness
  • Numbness
  • Problems with balance and movement

Who is diagnosed with oligodendrogliomas?

Oligodendrogliomas occur most often in people between the ages of 35 and 44, but can occur at any age. Oligodendrogliomas occur more often in males and are rare in children. They are most common in white and non-hispanic people. An estimated 11,757 people are living with this tumor in the United States.

What is the prognosis of oligodendrogliomas?

The likely outcome of the disease or chance of recovery is called prognosis.

Oligodendroglioma Prognosis

The relative 5-year survival rate for oligodendroglioma is 74.1% but know that many factors can affect prognosis. This includes the tumor grade and type, traits of the cancer, the person’s age and health when diagnosed, and how they respond to treatment. If you want to understand your prognosis, talk to your doctor.

What are the treatment options for oligodendrogliomas?

The first treatment for an oligodendroglioma is surgery, if possible. The goal of surgery is to obtain tissue to determine the tumor type and to remove as much tumor as possible without causing more symptoms for the person. Treatments after surgery may include radiation, chemotherapy, or clinical trials.

Clinical trials, with new chemotherapy, targeted therapy, or immunotherapy drugs, may also be available and can be a possible treatment option. Treatments are decided by the patient’s healthcare team based on the patient’s age, remaining tumor after surgery, tumor type, and tumor location.

Your oncologist might recommend a combination of medications - procarbazine, lomustine, and vincristine. A chemotherapy called temozolomide is also being studied in clinical trials.

Open Clinical Studies for Oligodendrogliomas

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Find doctors and nurses with experience treating this tumor.

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