Authors: Thomas PRM, Deutsch M, Kepner JL, et al.
Source: Journal of Clinical Oncology, 18(16), 2000, pg 3004-3011
Medulloblastoma is a primitive cerebellar tumor of neuroectodermal origin. It is a childhood malignancy (median age 5-6) that has a high propensity for neuraxis spread. Hence, standard treatment involves craniospinal irradiation. This carries a rate of toxicity, including significant nausea, vomiting, pancytopenia, and late neuropsychological and growth defects. This obviously would like to be avoided, if possible, especially in young children. This study compares treatment with standard dose craniospinal irradiation (CSI) with reduced dose CSI, in the attempt to maintain efficacy but reduce toxicity of treatment.
The long-term toxicities of CSI can be devastating, with reports of decrease in IQ and growth well-documented. However, in medulloblastoma, CSI is needed as this disease has a high propensity to spread throughout the neuraxis (15-30% in even standard risk patients). This attempt to reduce CSI dose was unsuccessful, as it resulted in a higher rate of failure, which is obviously a very serious result of inadequate treatment. In children, though, toxicity may outweigh even treatment failure-especially when the toxicities of treatment are as serious as those documented with CSI. This report did lead to an additional study, which used chemotherapy and lower doses of CSI to treat standard risk medulloblastoma (Packer et al, JCO 17(7), 2127, 1999). These results were very positive, and chemotherapy with reduced dose (23.4 Gy) CSI has become the accepted standard of care in standard risk medulloblastoma.