QOL-04. Histology, treatment, and extent of pretreatment hydrocephalus are major determents of neurocognitive outcome for survivors of pediatric posterior fossa tumors - report from the German HIT-studies

BACKGROUND: Cognitive impairments following pediatric brain tumors are generally attributed to tumor site, surgical intervention, complications as well as to nonsurgical treatment. We investigated impairments for patients with medulloblastoma (MB), ependymoma (EP) and low-grade glioma (LGG) of the cerebellum treated within the German pediatric brain tumor network to compare and rank major determents. PATIENTS+METHODS: Following protocol treatment, 245 patients with MB (n=106), EP (n=32), and cerebellar LGG (n=107, surgery only) were examined 2 + 5 years after diagnosis using the German “Neuropsychological-Basic-Diagnostic” (NBD) tool based on the Cattell-Horn-Carroll model for intelligence. Within this retrospective study, multiple linear regression models were applied. RESULTS: The MB+EP vs. LGG-cohort differed slightly in median age at diagnosis (8.7/6.1 years) and location (cerebellar hemispheres: 8%MB+EP/49.5%LGG), while sex-ratio, grade of resection, extent of pre-operative hydrocephalus were comparable. With smaller median tumor-volume in the MB+EP vs. LGG-cohort (34.1/44.1cm3), ranges broadly overlapped. Median scores of age-appropriate tests were in the lower normal range for all patients for fluid and crystallized intelligence, selective attention, visual-spatial processing (VSP) and verbal short-term memory (median=93-103), but distinctly below for processing speed (PS), and psychomotor speed abilities (PMS) (median=65-84). Higher doses of craniospinal irradiation (>23.4Gy/23.4Gy) resulted in lower scores for most domains for MB-patients compared to LGG-patients (e.g., PS-estimate: >23.4Gy:-27.71, p=0.026/23.4Gy:-9.93, p=0.286). EP-patients (surgery+54Gy local radiation) scored better than LGG-patients except for PS (estimate:-15.65, p=0.111). Impairments were accentuated with higher degrees of hydrocephalus (estimate:-7.64, p=0.103) in patients with incomplete resection (estimate:12.23, p=0.006) for PMS both hands. CONCLUSION: Following age-adapted comprehensive treatment, survivors of a cerebellar tumor show significant impairments of PMS abilities in our trials. Our data suggest that slow growing LGG impair neurocognitive development more than local radiotherapy for ependymoma, while craniospinal irradiation compromises VSP and PS in MB. Initial symptomatic intracranial pressure remains a strong predictor for general neuropsychological impairment.