LAUSR

BACKGROUND Female and male trajectories of cerebellar and lobar brain structures are sexually dimorphic, making sex a potential candidate moderator of neurocognitive late effects from radiation treatment. We sought to evaluate longitudinal neurocognitive functioning in male versus female children treated for posterior fossa brain tumors. METHODS 51 female and 63 male survivors of posterior fossa tumors completed neuropsychological testing at two time points. We included patients treated with surgical resection, chemotherapy, and radiation therapy. Multilevel mixed modeling was used to predict IQ score as a function of patient gender following treatment (~2 or ~4 years post treatment). Effect sizes were used as a measure of clinical significance. RESULTS Multilevel models resulted in a significant gender by time interaction (F = 6.69, p = .011). Female's cognitive scores were considerably higher compared to males at 4 years post treatment. Females demonstrated an average improvement of 7.61 standard score IQ points compared to a decline of 2.97 points for males at 4 year follow-up. Effect sizes for female IQ compared to male IQ at 4 years post-treatment were between .8 and .9. CONCLUSION Trajectories of neurocognitive functioning following posterior fossa tumor treatment differed between female and male children. Sexual dimorphism in radiation late effects may alter treatment decisions in children. Research into sex-specific neuroprotective mechanisms underlying neurocognitive development following pediatric brain tumor treatments is warranted.