Molecular changes in brain tumors: prognostic and therapeutic impact

This review focuses on recent advances in the molecular biology of the main primary brain tumors (gliomas, medulloblastomas, and ependymomas), with particular emphasis on prognostic markers and potential therapeutic targets.

Current biologic markers are useful for predicting prognosis (e.g. 1p/19q codeletion in grade 2 and 3 gliomas, nuclear beta-catenin expression in medulloblastoma) or response to the treatment (e.g. the methyl guanyl methyl transferase promoter methylation status). Recent gene profiling studies have identified specific molecular signatures that permit a molecular classification and that also provide new, potentially useful prognostic markers. The studies have also shown a striking parallel between central nervous system ontogenesis and the oncogenesis of brain tumors. By elucidating the underlying activated molecular pathways, these approaches provide the basis for a biologic therapy to target the critically activated pathways.

Important advances have been made in the biologic understanding, molecular subclassification, and identification of prognostic markers in brain tumors, thereby improving the current classifications. Such data provide a rational basis for current and future targeted biologically based strategies.