Each year, nearly 20,000 Americans are diagnosed with primary brain tumors, and the majority of these are malignant. Because these tumors arise from the brain and spread within the brain, they can produce a host of devastating neurologic problems, from seizures to personality change, to loss of memory and judgment, to paralysis. Conventional treatments for this disease that are available in the general medical community are not very effective, and most patients with malignant primary brain tumors live no more than 1-2 years after diagnosis.