Medulloblastoma in children

Medulloblastoma is the most common malignant brain tumor in childhood. Today, a multimodality therapeutic approach using surgery, chemotherapy and radiotherapy has been used to treat these patients. Radical surgical removal of medulloblastoma is a mainstem of successful oncologic treatment. Based on the extent of surgical resection, age at diagnosis, and presence of metastases, the risk stratifi cation for these tumors has been divided into standard risk patients and high risk patients. Standard risk patients are treated with postoperative adjuvant chemotherapy and craniospinal irradiation, and high risk patients receive similar postoperative therapy with higher doses of irradiation. Children younger than three years postoperatively receive only high dose chemotherapy avoiding craniospinal irradiation because of the negative eff ects of irradiation on higher cognitive functions at that age. In the last few years, there has been continuous progress in the understanding of molecular biology in pediatric medulloblastomas. New genetic methods enabled characterization of 4 main molecular subgroups of medulloblastomas (SHH, WNT, Group C and Group D) that have clear correlation in histopathologic specimens, clinical course, and prognosis of the disease. Children with WNT molecular subgroup have the best survival and good results of treatment, while children with Group C molecular subgroup have the worst prognosis. Therefore, children from WNT group might benefi t from reducing the standard quantities of therapy to reduce toxic eff ects on neurocognitive outcome, while children from C group would benefi t from more aggressive therapy. Using new molecular-based classifi cation methods for accurate patient stratifi cation and targeted individualized therapy, the patients with better molecular prognosis may be spared deleterious neurologic and neurocognitive side eff ects of unwarranted aggressive therapy.

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