Childhood Central Nervous System Embryonal Tumors Treatment (PDQ®): Treatment - Health Professional Information [NCI] - Treatment Option Overview for CNS Embryonal Tumors
Risk Stratification for Medulloblastoma
Risk stratification is based on neuroradiographic evaluation for disseminated disease, cerebrospinal fluid (CSF) cytological examination, postoperative neuroimaging evaluation for the amount of residual disease, and age of the patient. Patients older than 3 years with medulloblastoma have been stratified into the following two risk groups:
- Average risk: Children older than 3 years with tumors that are totally resected or near-totally resected (≤1.5 cm2 of residual disease) and no metastatic disease.
- High risk: Children older than 3 years with metastatic disease and/or subtotal resection (>1.5 cm2 of residual disease). Metastatic disease includes neuroradiographic evidence of disseminated disease, positive cytology in lumbar or ventricular CSF obtained more than 10 days after surgery, or extraneural disease. Children with tumors showing diffuse anaplasia, who otherwise would have been considered average risk, are assigned to the high-risk group.[2,3]
For younger children, in some studies for those younger than 3 years and for others younger than 4 or 5 years, similar separation into average-risk (no dissemination and ≤1.5 cm2 of residual disease) or high-risk (disseminated disease and/or >1.5 cm2 of residual disease) groups has been employed. Histologic findings of desmoplasia have also been used to connote a more favorable risk subgrouping, especially the medulloblastoma with extensive nodularity subgroup.
Assigning a risk group based on extent of resection and disease at diagnosis may not predict treatment outcome. Molecular genetic and histologic factors may be more informative. Although molecular subdivisions will likely change risk characterization in the future, they are not yet used to assign treatment in North American prospective studies.