Molecular heterogeneity in medulloblastoma with implications for differingtumor biology

Medulloblastomas and related primitive neuroectodermal tumors are the secon d most common malignant tumors of childhood. In spite of improvements in ca ncer therapy, these tumors are still associated with significant morbidity and mortality. Although these tumors share similar histologic features, rec ent 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 ne wer therapeutic techniques, such as gene therapy, for selective targeting o f critical genetic events in subsets of medulloblastomas. It is becoming in creasingly clear that in medulloblastomas, the morphologic similarity of "s mall blue" cells does not imply similar or shared molecular characteristics , with implications for differing tumor biology.