Background
The objective of this study was to evaluate the contribution of radiation dose to different intracranial structures on changes in intellectual function for children with brain tumors.
Methods
We evaluated children with brain tumors treated from 2005-2017 who had longitudinal neuropsychological assessments and available photon dosimetric data (if RT given). Full scale intelligence quotient (FSIQ) and index scores were evaluated (perceptual reasoning [PRI], processing speed [PSI], verbal comprehension [VCI] and working memory [WMI]). Multivariable linear mixed effects models were used to model endpoints, with age at RT and dose to different brain regions as fixed effects and patient-specific random intercepts. P-values (p*) were adjusted for multiple comparisons.
Results
Sixty-nine patients were included, 56 of whom received RT. Median neuropsychological follow-up was 3.2 years. Right temporal lobe mean dose was strongly associated with decline in FSIQ (p* = 0.005); with each gray increase in mean dose, there was a decrease of 0.052 FSIQ points per year. Dose to 50% (D50) of the supratentorial brain was associated with decline in PSI (p* = 0.006) and WMI (p* = 0.001). Right and left hippocampus D50 were individually strongly associated with declines in VCI (p* = 0.009 for each). Presence of ventriculoperitoneal shunt decreased FSIQ by 10 points.
Conclusions
We reported associations between dosimetry to specific brain regions and intellectual outcomes, with suggested avoidance structures during RT planning. These models can help clinicians anticipate changes in neurocognition post-RT and guide selection of an optimal RT plan.