New research proves that a change in a particular gene can identify which patients with a specific kind of brain cancer will respond better to treatment. Testing for the gene can distinguish patients with a more- or less-aggressive form of glioblastoma, the most common and an often-fatal type of primary brain cancer, and this can help guide therapy. The prospective study looked for a change in the MGMT gene in tumors from 833 glioblastoma patients.