Radiation doses to brain substructures associated with cognition in radiotherapy of pediatric brain tumors.

Authors Toussaint L, Indelicato DJ, Stokkevåg CH, Lassen-Ramshad Y, Pedro C, Mikkelsen R, Di Pinto M, Li Z, Flampouri S, Vestergaard A, Petersen JBB, Schrøder H, Høyer M, Muren LP

Source Acta Oncol. 2019 Oct;58(10):1457-1462. Publicationdate 04 Jul 2019

Abstract

Background

Several brain substructures associated with cognition (BSCs) are located close to typical pediatric brain tumors. Pediatric patients, therefore, have considerable risks of neurocognitive impairment after brain radiotherapy. In this study, we investigated the radiation doses received by BSCs for three common locations of pediatric brain tumor entities.

Material and methods

For ten patients in each group [posterior fossa ependymoma (PFE), craniopharyngioma (CP), and hemispheric ependymoma (HE)], the cumulative fraction of BSCs volumes receiving various dose levels were analyzed. We subsequently explored the differences in dose patterns between the three groups and used available dose-response models from the literature to estimate treatment-induced intelligence quotient (IQ) decline.

Results

Doses to BSCs were found to differ considerably between the groups, depending on their position relative to the tumor. Large inter-patient variations were observed in the ipsilateral structures of the HE groups, and at low doses for all three groups. IQ decline estimates differed depending on the model applied, presenting larger variations in the HE group.

Conclusion

While there were notable differences in the dose patterns between the groups, the extent of estimated IQ decline depended more on the model applied. This inter-model variability should be considered in dose-effect assessments on cognitive outcomes of pediatric patients.