Biologic Risk Stratification of Medulloblastoma: The Real Time Is Now

Many of us remember medulloblastoma as the proto-type malignant childhood brain tumor we learned about in medical school [1]. Typically, a child aged approximately 5 years presents with several weeks to months of nausea, vomiting, headaches, ataxia, and sometimes a turned-in eye or abducens nerve paresis. Subsequent head computed to-mography or magnetic resonance imaging reveals a some-what circumscribed cerebellar tumor and obstructive hy-drocephalus. Histologically, the WHO defines this small, round, blue-cell tumor with hyperchromatic nuclei and scant cytoplasm as a grade 4 neoplasm [2]. Because of its tendency to disseminate through the subarachnoid spaces and to form microscopic or bulky metastases in about a third of patients, craniospinal radiotherapy to a dosage of 36 Gy, with an additional radiation boost to the posterior