Surgery is usually the initial treatment for children with medulloblastoma, both to confirm diagnosis and to remove as much tumor as is safely possible. Evidence suggests that more extensive surgical resections are related to an improved rate of survival, primarily in children with nondisseminated disease at the time of diagnosis.[7,8] One study in high-risk patients utilized presurgical chemotherapy (after tumor biopsy) to reduce tumor bulk and make subsequent resection of the tumor easier. This small study did not demonstrate a high rate of survival, and postchemotherapy surgery did not seem easier and was not related to a reduced incidence of postoperative complications.
Postoperatively, children may have significant neurologic deficits caused by preoperative tumor-related brain injury, hydrocephalus, or surgery-related brain injury.[Level of evidence: 3iC] In addition, a significant number of patients with medulloblastoma will develop delayed onset of mutism, suprabulbar palsies, ataxia, hypotonia, and emotional lability. This constellation of findings has been termed the cerebellar mutism syndrome, and its etiology remains unclear, although cerebellar vermian damage has been postulated as a possible cause for the mutism.[11,12]; [Level of evidence: 3iC] In two Children's Cancer Group studies evaluating children with both average-risk and poor-risk medulloblastoma, the syndrome has been identified in nearly 25% of patients.[12,13]; [Level of evidence: 3iiiC] Many patients with this syndrome may manifest neurologic and neurocognitive sequelae posttreatment.[13,14]
Radiation therapy is usually initiated after surgery with or without concomitant chemotherapy.[15,16,17] To date, the best survival results for children with medulloblastoma have been obtained when radiation therapy is begun within 4 to 6 weeks postsurgery.[15,16,17,18]; [Level of evidence: 1iA]
Prospective randomized trials and single-arm trials suggest that adjuvant chemotherapy given during and after radiation therapy improves overall survival for children with both average-risk and poor-risk medulloblastoma.[14,15,16,17,18,19] Although medulloblastoma is often sensitive to chemotherapy, preradiation chemotherapy has not been shown to improve survival compared with treatment with radiation therapy and subsequent chemotherapy. In some prospective studies, preradiation chemotherapy has been related to a poorer rate of survival.[16,17,18,19]
Children of all ages are susceptible to the adverse effects of radiation on brain development. Debilitating effects on growth and neurologic/cognitive development have been frequently observed, especially in younger children.[20,21,22,23] For this reason, the role of chemotherapy in allowing a delay in the administration of radiation therapy has been and is being studied. Results suggest that chemotherapy can be used to delay and sometimes obviate the need for radiation therapy in 20% to 40% of children younger than 3 years with nondisseminated medulloblastoma.[24,25]; [Level of evidence: 3iiiC] Children are also at risk for long-term endocrine dysfunction.