The risk of radiation-induced neurocognitive impairment and the impact of sparing the hippocampus during pediatric proton cranial irradiation

Authors

  • Daniel Gram a Department of Oncology – Section of Radiotherapy, Rigshospitalet, Copenhagen, Denmark;b Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark; c Department of Clinical Oncology and Palliative Care, Radiotherapy, Zealand University Hospital, Næstved, Denmark
  • N. Patrik Brodin d Institute for Onco-Physics, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY, USA
  • Thomas Björk-Eriksson e Department of Oncology, Institute of Clinical Sciences, Sahlgrenska Academy at the University of Gothenburg, Sweden;f Regional Cancer Centre West, Gothenburg, Sweden
  • Karsten Nysom g Department of Paediatrics and Adolescent Medicine, The Juliane Marie Center, Rigshospitalet, Copenhagen, Denmark
  • Per Munck af Rosenschöld b Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark;h Radiation Physics - Department of Hematology, Oncology and Radiation Physics, Skåne University Hospital, Lund, Sweden;i Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden

DOI:

https://doi.org/10.1080/0284186X.2023.2176253

Keywords:

Neurocognitive impairment, normal tissue complication probability, tumor control probabilitycraniospinal irradiationhippocampal avoidancepediatric hippocampus, craniospinal irradiation, hippocampal avoidance, pediatric hippocampus

Abstract

Background and purpose

Hippocampus is a central component for neurocognitive function and memory. We investigated the predicted risk of neurocognitive impairment of craniospinal irradiation (CSI) and the deliverability and effects of hippocampal sparing. The risk estimates were derived from published NTCP models. Specifically, we leveraged the estimated benefit of reduced neurocognitive impairment with the risk of reduced tumor control.

Material and methods

For this dose planning study, a total of 504 hippocampal sparing intensity modulated proton therapy (HS-IMPT) plans were generated for 24 pediatric patients whom had previously received CSI. Plans were evaluated with respect to target coverage and homogeneity index to target volumes, maximum and mean dose to OARs. Paired t-tests were used to compare hippocampal mean doses and normal tissue complication probability estimates.

Results

The median mean dose to the hippocampus could be reduced from 31.3 GyRBE to 7.3 GyRBE (p < .001), though 20% of these plans were not considered clinically acceptable as they failed one or more acceptance criterion. Reducing the median mean hippocampus dose to 10.6 GyRBE was possible with all plans considered as clinically acceptable treatment plans. By sparing the hippocampus to the lowest dose level, the risk estimation of neurocognitive impairment could be reduced from 89.6%, 62.1% and 51.1% to 41.0% (p < .001), 20.1% (p < .001) and 29.9% (p < .001) for task efficiency, organization and memory, respectively. Estimated tumor control probability was not adversely affected by HS-IMPT, ranging from 78.5 to 80.5% for all plans.

Conclusions

We present estimates of potential clinical benefit in terms of neurocognitive impairment and demonstrate the possibility of considerably reducing neurocognitive adverse effects, minimally compromising target coverage locally using HS-IMPT.

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Additional Files

Published

2023-02-01

How to Cite

Gram, D., Brodin, N. P., Björk-Eriksson, T., Nysom, K., & af Rosenschöld, P. M. (2023). The risk of radiation-induced neurocognitive impairment and the impact of sparing the hippocampus during pediatric proton cranial irradiation. Acta Oncologica, 62(2), 134–140. https://doi.org/10.1080/0284186X.2023.2176253

Issue

Vol. 62 No. 2 (2023): Acta Oncologica

Section

Articles