Brain chemical clues may predict who lives longer with aggressive cancer

This study looks at whether certain brain chemicals can predict survival in people with glioblastoma (a fast-growing brain cancer) that has returned after standard treatment. Researchers will measure these chemicals with special scans 7 and 28 days after starting the drug bevacizumab. The goal is to find out early which patients are likely to benefit from this expensive treatment and avoid using it in those who won't.