The American Cancer Society anticipates that 16,500 patients will be diagnosed with primary malignant tumors of the central nervous system in 2000, with about 200,000 individuals presenting with brain metastases. The advances in the treatment of solid tumors have contributed significantly to the major increase in metastatic cancers to the brain. Of the primary malignant tumors of the brain, more than 50% are high-grade gliomas; the incidence has been...