Malignant astrocytomas epidemiology and demographics

Epidemiology and Demographics
Brain tumors account for about 2% of all cancers, and are about 1/5 as common as breast or lung cancer. More than 50% of brain tumors are secondary, or metastatic from another site. Primary brain tumors originate from the brain parenchyma, meninges, cranial nerves or other intracrainial structures. In 1998, there were approximately 18,000 new cases of primary brain tumors. There is national and international data suggesting the incidence of these tumors is increasing. Gliomas, tumors of the neuroglia, arise from the oligodendrocytes, ependymal cells and the astrocytes.

Collectively astrocytomas are the most common type of primary brain tumor and account for 80%. These tumors are most frequently discovered in middle age. The approximate median survival is 94 months for Grade I-II, 12 months for Grade III and 5 months for Grade IV.