A glioma brain tumor occurs in the central nervous system, states Mayo Clinic. Glioma brain tumors originate from supportive cells that surround the body’s nerve cells and help them to function. Gliomas are categorized as astrocytomas, ependymomas or oligodendrogliomas, depending on the type of supportive cells that cause them.
WebMD attributes the risk of gliomas to prior radiation treatment and some genetic disorders. Astrocytomas, which originate from astrocytes, represent almost 50 percent of all brain tumors. These tumors spread throughout the normal brain tissue, making the tumor hard to treat. Doctors categorize astrocytomas by their growth rate.
Ependymomas make up to 3 percent of all brain tumors, reports WebMD. These tumors are more common in children than adults, making up 10 percent of all brain tumors in kids. These tumors originate from ependymal cells located in the brain. Ependymomas don’t spread into normal brain tissues, making these tumors treatable. However, ependymomas have a high possibility of recurring, so WebMD considers them to be malignant.
An oligodendroglioma arises from oligodendrocytes, supportive cells found in the cerebrum, claims John Hopkins Medicine. This type of tumor accounts for nearly 4 percent of primary brain tumors. Oligodendrogliomas have better prognoses than astrocytomas and ependymomas.