Glioma

A glioma is a tumor that forms when glial cells grow out of control. Normally, these cells support nerves and help your central nervous system work. Gliomas usually grow in the brain, but can also form in the spinal cord.

Gliomas are malignant (cancerous), but some can be very slow growing. They’re primary brain tumors, meaning they originate in the brain tissue. Gliomas don’t usually spread outside of the brain or spine, but are life-threatening because they can:

• Be hard to reach and treat with surgery.
• Grow into other areas of the brain.

Are there different types of gliomas?

There are three main types of gliomas, grouped by the type of glial cell they start in. Some gliomas contain multiple types of cells. Healthcare providers call these mixed gliomas. They categorize each type of glioma as low-, mid- or high-grade based on how fast they grow and other features.

Gliomas include:

• Astrocytomas, including glioblastomas and diffuse intrinsic pontine gliomas (DIPGs): These tumors start in cells called astrocytes. Glioblastomas are astrocytomas that are very aggressive or grow fast. They are the most common malignant brain tumor in adults. Astrocytomas are common gliomas in children. A rare but very aggressive form of brain cancer in children is DIPG. It forms in the brain stem and mostly affects children.
• Ependymomas: These tumors start in ependymocytes, a type of glial cell. Ependymomas usually form in the ventricles of the brain or the spinal cord. They may spread through cerebrospinal fluid (the fluid that surrounds and protects the brain and spinal cord), but don’t spread outside the brain or spine. Ependymomas make up about 2% of all brain tumors. They’re more common in children than adults.
• Oligodendrogliomas: These tumors start in glial cells called oligodendrocytes. Oligodendrogliomas tend to grow more slowly but can become more aggressive over time. Like ependymomas, they rarely spread outside the brain or spine. They’re more common in adults than children. Oligodendrogliomas account for about 1% to 2% of all brain tumors.

Who is at risk of getting a glioma?

Anyone can develop a glioma, but the following factors may increase your risk:

• Age: Gliomas are most common in older adults (over 65) and children (under 12).
• Ethnicity: White people may be more likely to develop gliomas than other races.
• Family history: Some inherited genetic disorders may increase your risk of gliomas.
• Gender: Gliomas are slightly more common in men than women.
• Radiation or toxin exposure: Repeated or prolonged exposure to radiation or certain chemicals may increase your risk.

How common are gliomas?

About 80,000 people are newly diagnosed with primary brain tumors each year in the U.S. Approximately 25% of these are gliomas.