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Oligodendroglioma is a type of brain tumor known as a glioma. Oligodendroglioma gets its name because the tumor cells look like oligodendrocytes, cells that form a protective cover for nerves in the brain.
Oligodendrogliomas most often develop in the white matter of the cerebrum. About half occur in the frontal lobe.
Most oligodendrogliomas occur in adults. They are very rare in children and teens. Less than 1% of brain tumors in children under 14 years of age are oligodendrogliomas.
Oligodendrogliomas can be low grade (grade II) or high grade (grade III). These tumors are often diffuse and may not have well-defined borders. Treatment usually includes surgery to remove as much of the tumor as possible. Radiation therapy is often used to kill remaining cancer cells. Chemotherapy may also be used. Survival rates for children with oligodendroglioma depend on the tumor grade and success of surgery. Patients with low-grade tumors that are completely removed by surgery have a survival rate greater than 90%.
Oligodendrogliomas are often slow growing. The tumor may be present for years before it causes problems. Signs and symptoms of oligodendroglioma depend on several factors including child’s age, tumor size, location of the tumor, and how fast it grows.
Oligodendroglioma symptoms may include:
About half of patients experience seizures before diagnosis. Most patients (about 80%) will have seizures at some point during the course of their illness.
Doctors test for oligodendroglioma in several ways.
Oligodendroglioma tumors are grouped by how they look under the microscope. The more abnormal the cells look, the higher the grade. Oligodendrogliomas are usually grade II or III.
In the past, a diagnosis of oligodendroglioma was based mainly on how the tumor cells looked under a microscope. However, doctors are learning more about specific molecular changes and gene mutations (DNA changes) that occur in the cells of the tumor. Most oligodendrogliomas have a specific molecular marker that help in the diagnosis. First is a gene mutation known as an IDH-mutation, which may be seen in different types of gliomas. Oligodendrogliomas are identified based on an IDH1 or IDH2 mutation. Usually, oligodendrogliomas also have a change in chromosomes called a 1p/19q codeletion. However, pediatric oligodendrogliomas, especially in younger children, may not have these molecular features. In these cases, doctors rely on imaging tests, pathology, and clinical features to make a diagnosis. Understanding the specific changes in tumor cells can help doctors plan treatments and develop better therapies in the future.
Oligodendroglioma is much more common in adults, and less is known about the prognosis for pediatric patients. Overall, children tend to have better outcomes compared to adults. For pediatric oligodendroglioma, the overall 5-year survival rate is greater than 80%. However, treatment outcomes can vary widely based on the success of surgery, age at diagnosis, molecular features of the tumor, and other factors. In addition, recurrence of disease is common, even among long-term survivors.
Factors that influence outcome include:
Treatment of oligodendroglioma depends on the type of tumor, its location, and whether it has spread or come back. Aggressive tumors need more intensive treatment. Doctors also consider the age of the patient. Radiation therapy is not used in very young children because of the potential side effects.
Surgery to remove as much of the tumor as possible is the main treatment for oligodendroglioma. The goal is gross total resection, or complete removal of the tumor. However, it may not always be possible to remove the entire tumor due to risk of damage to nearby brain structures and the diffuse nature of oligodendroglioma. In some cases, surgery may not be possible due to the location of the tumor. Some patients with low-grade tumors may have surgery alone followed by observation. Other patients may have surgery and then receive radiation and/or chemotherapy.
Radiation therapy may be used after surgery to kill cancer cells left behind. Radiation therapy depends on the type and location of the tumor and the age of the child.
Chemotherapy is sometimes used in addition to surgery and radiation therapy, especially for high grade tumors. Chemotherapy may be used in infants and young children to delay the use of radiation therapy. Chemotherapy used for oligodendroglioma includes procarbazine, lomustine (CCNU), and vincristine (PCV regimen) and temozolomide. Other types of chemotherapy may also be used, especially within a clinical trial. Some chemotherapy medicines used to treat oligodendroglioma may cause fertility problems in the future. Depending on the type of chemotherapy planned, families may want to talk with their care team about options to help protect fertility.
Targeted therapies work by acting on or targeting specific features of the tumor such as genes and proteins.
Care for patients with oligodendroglioma should include appropriate referrals to support services such as neurology, rehabilitation therapy, school services, and psychology. After treatment for oligodendroglioma, patients will have regular MRI scans to monitor for recurrence. Steroid and anti-seizure medications may be needed for a period of time.
Recovery and long-term effects of oligodendroglioma in children and teens depend on features of the tumor and treatments received. Ongoing follow-up care, laboratory tests, and routine MRI scans are needed to monitor patients for recurrence or progression of disease. The care team will set a schedule based on individual patient needs.
Low-grade gliomas, including some oligodendrogliomas, are often a chronic or long-term disease. Although long-term survival from low-grade glioma is high, the tumor often comes back or progresses over time. A patient may need additional treatments over many years of follow-up. This means the patient is at risk for more treatment- or tumor- related complications. There may also be times when the tumor shows growth on a scan, but the care team recommends observation (watchful waiting) instead of treatment. Good communication and trust among patient, family, and care team are critical to aid in decision making and disease management.
Reviewed: January 2020