Oligodendroglioma

Oligodendroglioma

Oligodendrogliomas come from oligodendrocytes, one of the types of cells that make up the supportive, or glial, tissue of the brain. Oligodendrogliomas are generally soft, grayish-pink tumors. They often contain mineral deposits (called calcifications), areas of hemorrhage, and/or cysts. Under the microscope, these tumor cells appear to have “short arms,” or a fried-egg shape. Sometimes oligodendrogliomas are mixed with other cell types.

Location

Oligodendrogliomas can be found anywhere within the cerebral hemisphere of the brain, although the frontal and temporal lobes are common locations.

Symptoms

Common signs of an oligodendroglioma are seizures, headaches, and personality changes. Other symptoms may also be noted including persistent weakness or numbness in an arm or leg or changes related to thinking, learning, concentrating, problem-solving, and decision-making. Symptoms may vary by location and size of the tumor.

Treatment

If the tumor is located in a region of the brain that is accessible, then the usual treatment for oligodendroglioma is surgical removal of as much of the tumor tissue as possible. In instances in which the tumor is able to be removed, surgery may be the only treatment needed. Biopsy is typically performed on tumors that are not accessible to confirm the diagnosis and help guide treatment.

If some of the tumor remains (also called “residual” tumor) or if the tumor has molecular characteristics that suggest it may be more likely to recur, radiation treatment may be recommended following surgery. Radiation therapy generally takes place over the course of a six-week time period and may be given along with chemotherapy.

Depending upon the amount of tumor that is not able to be removed (residual tumor) and the molecular characteristics of the tumor itself, chemotherapy may be suggested to treat the remaining tumor. There are several types of chemotherapy that may be used as well as several ways in which the treatment may be received (i.e., via a pill or an intravenous injection).

Regular MRI scans are recommended following the diagnosis of oligodendroglioma, generally at least once per year. Patients with seizures will need to be followed for their seizure medication.

A recurring oligodendroglioma may be treated with surgery, particularly when the time between initial diagnosis and recurrence is extended. In this way, the diagnosis can be updated to reflect any molecular changes that may have occurred over time, whether they be naturally occurring or associated with any treatments including radiation, chemotherapy, or immunotherapy. They may also be treated with radiation therapy, depending on whether or how much radiation was given after the original diagnosis. Chemotherapy/immunotherapy and clinical trials are additional options.

Prognosis

Prognosis means a prediction of outcome. This information is usually based on information gathered from groups of people with the same disease. It is important to remember these statistics are not individualized.

The 5-year relative survival rates for oligodendroglioma by age group are as follows:5

Children (0-14): 94.0%

Adolescents and Young Adults (15-39): 92.2%

Adults (40+): 76.8%

Incidence

Oligodendrogliomas are estimated to account for 1.3% of brain tumors in the United States with approximately 1,100 new diagnoses in the United States each year.

Age Distribution

Oligodendrogliomas are most common in adults and most often occur between the ages of 20-40. Although these tumors are found in both men and women, they tend to occur more often in men. Oligodendrogliomas are very rare in children under the age of 15.

Risk Factors

Although all tumors (including oligodendroglioma) are caused by genetic changes, the exact 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.

Molecular Classification

Oligodendrogliomas are a type of glioma that have mutations in one of two genes called IDH1 and IDH2 and are missing the two chromosomal arms, 1p and 19q. These tumors are thus named Oligodendroglioma, IDH-mutant, and 1p/19q-codeleted. Oligodendrogliomas are defined as either grade 2 or 3, with grade 3 tumors associated with a more rapid growth. In addition, grade 3 tumors appear to have abnormalities on chromosomes 9 or 10, along with unusual amounts of growth factors and proteins, which are thought to contribute to the more rapid growth of these gliomas.

Content last reviewed:

April 2022

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