Treatment of Medulloblastoma: Chemotherapy

Medulloblastoma (MB) is one of the most common malignant brain tumors in childhood. Its origin is from the cerebellar vermis or from one of cerebellar hemispheres. Its extracerebellar counterparts are the primitive neuroectodermal tumors known as PNETs. Among pediatric embryonal central nervous system tumors, MB generally shows a better prognosis with 5-year survival rates of up to 70 % in standard-risk patients. The standard risk identifies patients fulfilling following criteria: total or subtotal resection, age over 3 years, and localized disease without dissemination. Chemotherapy modified the prognosis of MB since 1976 when the first trial of the International Society of Paediatric Oncology (SIOP I) introduced adjuvant chemotherapy (vincristine, lomustine, and prednisone). Now, we consider MB a chemoresponsive tumor and chemotherapy plays a role together with surgery and radiotherapy. Resistance to treatments is on study: biological differences may explain different behavior of neoplastic cells and different fates between patients inside the same risk group. Ongoing research will point to the knowledge of deregulation of embryogenetic signalling pathways involved in the pathogenesis of MB and in self-maintenance of tumoral stem cells. Future therapeutic trials will have different stratification of patients based on biological markers.