Cancer on the Brain

At the Association for Molecular Pathology's annual meeting in San Jose last week, the University of Pittsburgh's Marina Nikiforovna offered clinicians a novel way to distinguish between classifications of glioblastomas. Mutations of the IDH1 and IDH2 genes were discovered in 2008, and a high frequency of brain tumors — between 60 and 94 percent — show those mutations, Nikiforovna said. In fact, researchers speculate that a mutation in the IDH pathway is an early event of glial genesis. Under normal circumstances, IDH has a role in preventing oxidative damage to cells, but when it mutates there is an increased susceptibility to oxidative stress and an accumulation of 2-hydroxygluterate, which leads to gliomal development, Nikiforovna said. In diagnosis, identifying an IDH mutation can serve as a marker of a grade II glioblastoma, as grade I tumors do not show IDH mutations. The identification can also serve to help clinicians tell the difference between brain cancers and other cancers that may metastasize to the brain, as only gliomas have IDH mutations, Nikiforovna said. The identification can also be used as a prognostic tool — patients with IDH mutation-positive tumors have a better prognosis than patients with IDH mutation-negative tumors. Identification of IDH mutations "even might be an independent prognostic marker," Nikiforovna said. At present, there are no therapies for glioblastoma that target IDH, but the mutation could provide a new target for treatment, she added.