What is oligoastrocytoma? Oligoastrocytoma belong to a group of brain tumors called “gliomas.” Gliomas are tumors that come from the glial, or supportive, cells of the brain. There are several different types of gliomas. An oligoastrocytoma is a “mixed glioma” tumor, which contains both abnormal oligodendroglioma and astrocytoma cells. Location These tumors can be found anywhere within the cerebral hemispheres of the brain, although the frontal and temporal lobes are the most common locations. Description Oligoastrocytomas (grade II) are considered low-grade tumors. They generally grow at a slower rate than anaplastic oligoastrocytomas (grade III), which are malignant. Oligoastrocytomas may evolve over time into anaplastic oligoastrocytomas. Symptoms The most common symptoms of oligoastrocytoma are seizures, headaches, and personality changes. Other symptoms vary by location and size of the tumor. Incidence About 40% of primary brain tumors are gliomas. Mixed gliomas, primarily oligoastrocytomas, account for 5-10% of gliomas and 1% of all brain tumors. Oligoastrocytomas develop in young and middle-aged adults (ages 30 to 50). Very few children are diagnosed with oligoastrocytoma. Cause Like many tumor types, the exact cause of oligoastrocytoma is not known.