Childhood medulloblastoma: the paradigm shift in molecular stratification and treatment profile

Medulloblastoma is the most common malignant brain tumor of childhood, accounting for nearly 25% to 30% of primary central nervous system tumors in children younger than 18 years of age. Risk stratification into low and high risk categories has been based on age of clinical presentation, extent of postsurgical residual tumor, and disease dissemination. The World Health Organization (WHO) in 2007 recognized 5 histological subtypes as classic, anaplastic, large cell, desmoplastic/nodular, and medulloblastoma with extensive nodularity. Recent work with gene expression profiling along with histological classification has generated a novel combined histopathological and molecular stratification scheme into 4 subgroups (Wnt, Shh, group 3, and group 4). This could now help to identify patients who might benefit from dose escalation and de-escalation of therapy. Restratification brings optimism in treating these patients as scholars now have the ability to profile a more targeted therapy approach. This review discusses the literature regarding this new research endeavor.