Malignant astrocytoma, glioblastoma multiforme (WHO grade IV), and anaplastic astrocytoma (WHO grade III) are still the most common primary cerebral neoplasms in adults. These highly invasive tumors have a strong predilection for cerebral hemispheres. Glioblastoma multiforme (GBM) comprises 80% of malignant gliomas. While malignant astrocytomas comprise only 2% of all adult tumors at a rate of 5 cases per 100,000 adults per year, their malignant nature makes them the fourth greatest cause of cancer death . Malignant astrocytomas are associated with a slight male to female preference (1.6:1.0). The peak age at onset for GBM is in the sixth or seventh decade, whereas anaplastic astro-cytoma (AA) usually presents in the fourth or fifth decade. GBM (0.2/100,000 per year) and AA (0.5/100,000 per year) rarely occur in children less than 14 years of age. While malignant astrocytomas occur less commonly in African-Americans, no national differences in incidence have been consistently demonstrated after racial and age correction. Recent evidence suggests that the incidence of GBM and AA have doubled over the past decade. While the significance of this observation is unclear, many believe this to be a result of the increased use of MRI and CT.
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