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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. 

Author information

Kahalley LS1, Ris MD2, Grosshans DR2, Okcu MF2, Paulino AC2, Chintagumpala M2, Moore BD2, Guffey D2, Minard CG2, Stancel HH2, Mahajan A2.​

1Lisa S. Kahalley, M. Douglas Ris, M. Fatih Okcu, Murali Chintagumpala, Danielle Guffey, Charles G. Minard, and Heather H. Stancel, Baylor College of Medicine, Houston; and David R. Grosshans, Arnold C. Paulino, Bartlett D. Moore, and Anita Mahajan, The University of Texas MD Anderson Cancer Center, Houston, TX. kahalley@bcm.edu.

2Lisa S. Kahalley, M. Douglas Ris, M. Fatih Okcu, Murali Chintagumpala, Danielle Guffey, Charles G. Minard, and Heather H. Stancel, Baylor College of Medicine, Houston; and David R. Grosshans, Arnold C. Paulino, Bartlett D. Moore, and Anita Mahajan, The University of Texas MD Anderson Cancer Center, Houston, TX.