Medical News Today -- In 2007, an estimated 20,500 new cases of primary malignant brain and central nervous system tumors were diagnosed, of which 16,605 were estimated to be gliomas, the most prevalent type of malignant brain tumor in adults. Gliomas arise from the supporting cells of the brain, called the glia. These cells are subdivided into astrocytes, ependymal cells and ologodendroglial cells (or oligos). These tumors are graded from the lowest grade 1 to highest grade 4, with glioblastoma multiforme (GBM) being the highest grade and deadliest type of glioma. About 50 percent of all gliomas diagnosed annually are high-grade GBMs.
