QOL-13. NEUROCOGNITIVE OUTCOMES ACCORDING TO RISK-ADAPTED TREATMENT REGIMENS FOR CHILDREN OLDER THAN 4 WITH MEDULLOBLASTOMA AND POSTERIOR FOSSA EPENDYMOMA – RESULTS OF THE HIT2000 TRIAL

Abstract OBJECTIVES Reduced neuropsychological outcomes are a major concern in pediatric patients with malignant brain tumors. We aimed to estimate decline in cognitive function according to treatment regimens. METHODS Cross-sectional analysis of cognitive functions tested with the Neuropsychological Basic Diagnostic tool (NBD) in 279 patients >4 years at diagnosis (median: 8.66; range: 4.01–18.98) with medulloblastoma (n=110, 23.7–25.0Gy CSI; n=131, >30Gy CSI) or posterior fossa ependymoma (n=38 local radiotherapy) who participated in the HIT-2000 trial. Multivariable regression analysis was conducted to adjust for postoperative cerebellar mutism syndrome, preoperative hydrocephalus, postoperative shunt placement, the interval between diagnosis and assessment, sex and age. RESULTS Mean time from diagnosis to assessment was 5.1 years. Increasing CSI-dose was significantly associated with a deterioration in performance of most subtests, particularly in areas of fluid intelligence (mean z-values per test for no CSI/23.4Gy/>30Gy respectively: matrix reasoning:-0.40/-0.52/-0.98, p<.001), short-term memory (number recall: -0.07/-0.58/-0.64, p=.002), visuo-spatial skills (visual-motor integration:-0.49/-0.68/-1.12, p<.001) and fine motor skills (dominant-hand:-1.09/-1.80/-2.12, p=.008; non-dominant-hand:-1.47/-2.59/-2.82, p=.003; bimanual coordination:-1.33/-2.68/-2.76, p=.001). These differences were retained after adjustment for confounding variables. Within medulloblastoma patients treated with >30Gy CSI, selective attention, but no other function was reduced in patients treated with pre-radiotherapy chemotherapy including intraventricular MTX (selective attention (with chemotherapy/without chemotherapy mean z-values: -0.66/0.00, p=.006)). Patients with SHH-activated medulloblastoma did significantly better than WNT or Group3/Group4 medulloblastoma patients in fluid intelligence and fine motor skills. CONCLUSION CSI dose among other highly relevant factors had significant effects on neuropsychological outcome. Pre-radiotherapy intraventricular MTX had only minor effects. Patients with SHH-activated medulloblastomas showed a more favorable outcome when compared to patients in the other subgroups.