Molecular Heterogeneity in Medulloblastoma With Implications for Differing Tumor Biology

Medulloblastomas and related primitive neuroectodermal tumors are the second most common malignant tumors of child-hood. In spite of improvements in cancer therapy, these tumors are still associated with significant morbidity and mortality. Although these tumors share similar histologic features, recent molecular studies suggest that they could represent a genetically mixed group of tumors. The genetic events that might play a role in the biology of these tumors also could allow a molecular subtyping of medulloblastomas. Such molecular subtyping of medulloblastomas could allow for the use of newer therapeutic techniques, such as gene therapy, for selective targeting of critical genetic events in subsets of medullo-blastomas. It is becoming increasingly clear that in medulloblastomas, the morphologic similarity of "small blue " cells does not imply similar or shared molecular characteristics, with implications for differing tumor biology. (J Child Neurol 1999;14:411-417). Medulloblastomas and related primitive neuroectodermal tumors represent a significant group of central nervous system tumors that occur predominantly in the pediatric pop-ulation and less frequently in the adult population. They account for 25 % of childhood intracranial tumors and ar