Glioma
This group comprises anaplastic astrocytomas and glioblastoma multiforme. Whereas the median overall survival of anaplastic (WHO grade III) gliomas is approximately 3 years, glioblastoma multiforme has a poor median overall survival of c. 15 months.
Oligoastrocytoma
These types of glial cells that become cancerous are involved with insulating and regulating the activity of neuron cells in the central nervous system. Often called a "mixed glioma", about 2.3% of all reported brain tumors are diagnosed as oligoastrocytoma. The median age of diagnosis is 42.5. 
Oligoastrocytomas, like astrocytomas and oligodendrogliomas, can be divided into low-grade and anaplastic variant, the latter characterized by high cellularity, conspicuous cytologic atypism, mitotic activity and, in some cases, microvascular proliferation and necrosis.