Neuropsychologic functioning of survivors of childhood medulloblastoma randomized to receive conventional or reduced-dose craniospinal irradiation: A Pediatric Oncology Group study

Purpose: The purpose of this study was to test the hypothesis that survivors of medulloblastoma who were younger at diagnosis and those who received standard-dose cranial irradiation (SRT) of 36 Gy would have a lower performance on standardized tests of cognitive function and achievement than children who were older and those treated with reduced-dose cranial irradiation (RRT) of 23.4 Gy. Patients and Methods: Eligible patients had been treated on Pediatric Oncology Group (POG) study 8631 for low-risk medulloblastoma that randomized patients to receive RRT or SRT after surgical resection. Those who were alive and free of progressive disease 6.1 to 9.9 years from completion of treatment were eligible for this study. Of the 35 eligible patients, 22 patients (13 SRT, nine RRT) participated in a battery of tests that included intellectual and academic development as well as ratings of health-related quality of life. Results: Patients were stratified by treatment group (SRT v RRT) and into younger (Y) and elder (O) groups by the median age at diagnosis (8.85 years), which resulted in four groups that we hypothesized would show neuropsychologic test scores in the following order: Y/SRT less than Y/RRT less than O/SRT less than O/RRT. Evidence to support the hypothesized ordering of groups in terms of neuropsychologic toxicity was obtained with regard to Performance Intelligence Quotient (IQ), Full Scale IQ, Attention, Reading, and Arithmetic. Conclusion: Children treated for medulloblastoma experienced less severe neuropsychologic toxicity when treated with 23.4 Gy instead of 36 Gy cranial irradiation. Older children experienced less toxicity than children who were younger at the time of irradiation.