Comparing Intelligence Quotient Change After Treatment With Proton Versus Photon Radiation Therapy for Pediatric Brain Tumors

Abstract

Purpose Compared with photon radiation (XRT), proton beam radiation therapy (PBRT) reduces dose to normal tissues, which may lead to better neurocognitive outcomes. We compared change in intelligence quotient (IQ) over time in pediatric patients with brain tumors treated with PBRT versus XRT. Patients and Methods IQ scores were available for 150 patients (60 had received XRT, 90 had received PBRT). Linear mixed models examined change in IQ over time since radiation therapy (RT) by RT group, controlling for demographic/clinical characteristics. Craniospinal and focal RT subgroups were also examined. Results In the PBRT group, no change in IQ over time was identified (P = .130), whereas in the XRT group, IQ declined by 1.1 points per year (P = .004). IQ slopes did not differ between groups (P = .509). IQ was lower in the XRT group (by 8.7 points) versus the PBRT group (P = .011). In the craniospinal subgroup, IQ remained stable in both the PBRT (P = .203) and XRT groups (P = .060), and IQ slopes did not differ (P = .890). IQ was lower in the XRT group (by 12.5 points) versus the PBRT group (P = .004). In the focal subgroup, IQ scores remained stable in the PBRT group (P = .401) but declined significantly in the XRT group by 1.57 points per year (P = .026). IQ slopes did not differ between groups (P = .342). Conclusion PBRT was not associated with IQ decline or impairment, yet IQ slopes did not differ between the PBRT and XRT groups. It remains unclear if PBRT results in clinically meaningful cognitive sparing that significantly exceeds that of modern XRT protocols. Additional long-term data are needed to fully understand the neurocognitive impact of PBRT in survivors of pediatric brain tumors.

Attention, processing speed, and executive functioning in pediatric brain tumor survivors treated with proton beam radiation therapy

“…While previous reports have identified some vulnerability in processing speed skills among pediatric brain tumor survivors treated with PBRT [13–15], to our knowledge, this is the first report on attention and executive functioning outcomes in this population. In our sample of survivors who were more than three years post-PBRT on average, sustained attention was found to fall within age-expectation.…”

“…In a large retrospective comparison of survivors of pediatric brain tumors, we found no statistically significant IQ decline or impairment in survivors treated with PBRT ( n = 90; mean ( M ) follow-up = 2.7 years), while survivors treated with XRT showed statistically significant IQ decline ( n = 60; M follow-up = 5.4 years); yet, the IQ trajectories (i.e., the slope or the amount of IQ change over time) did not differ between groups [13]. Another recent study examining intellectual ability in 43 pediatric survivors of medulloblastoma treated with PBRT-based craniospinal irradiation (CSI; M follow-up = 5.2 years) found significant decline in processing speed and verbal comprehension, with global IQ decline observed only in patients younger than 8 years old at treatment [14].…”

Controversy over the Use of Proton Therapy for the Treatment of Tumors of Central Nervous Systém

“…Klinickým hodnocením IQ skóre se zabývala studie Kahalley et al [32]. Studie zahrnovala 150 pediatrických pa cientů ozařovaných pro mozkové nádory, z nichž 60 bylo léčeno fotony a 90 PBT.…”

The role of image-guided intensity modulated proton therapy in glioma

“…36 While, as in adults, no clinical data have definitely proven the superiority of proton therapy, evidence is beginning to emerge suggesting a potential benefit in terms of cognitive preservation. 37 However, further prospective study is needed.…”