Impact of RBE variations on risk estimates of temporal lobe necrosis in patients treated with intensity-modulated proton therapy for head and neck cancer

Authors

  • Grete May Engeseth Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA; Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway; Department of Clinical Science, University of Bergen, Bergen, Norway
  • Liv Bolstad Hysing Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway; Department of Physics and Technology, University of Bergen, Bergen, Norway
  • Pablo Yepes Physics and Astronomy Department, Rice University, Houston, TX, USA
  • Helge Egil Seime Pettersen Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
  • Radhe Mohan Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX, USA
  • Clifton Dave Fuller Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
  • Camilla Hanquist Stokkevåg Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway; Department of Physics and Technology, University of Bergen, Bergen, Norway
  • Richard Wu Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
  • Xiaodong Zhang Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
  • Steven Jay Frank Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
  • Gary Brandon Gunn Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX, USA

DOI:

https://doi.org/10.1080/0284186X.2021.1979248

Keywords:

Oral anticancer treatment, cancer, adherence, illness perceptions, medication beliefs, psychosocial determinants

Abstract

Background

Temporal lobe necrosis (TLN) is a potential late effect after radiotherapy for skull base head and neck cancer (HNC). Several photon-derived dose constraints and normal tissue complication probability (NTCP) models have been proposed, however variation in relative biological effectiveness (RBE) may challenge the applicability of these dose constraints and models in proton therapy. The purpose of this study was therefore to investigate the influence of RBE variations on risk estimates of TLN after Intensity-Modulated Proton Therapy for HNC.

Material and Methods

Seventy-five temporal lobes from 45 previously treated patients were included in the analysis. Sixteen temporal lobes had radiation associated Magnetic Resonance image changes (TLIC) suspected to be early signs of TLN. Fixed (RWDFix) and variable RBE-weighed doses (RWDVar) were calculated using RBE = 1.1 and two RBE models, respectively. RWDFix and RWDVar for temporal lobes were compared using Friedman’s test. Based on RWDFix, six NTCP models were fitted and internally validated through bootstrapping. Estimated probabilities from RWDFix and RWDVar were compared using paired Wilcoxon test. Seven dose constraints were evaluated separately for RWDFix and RWDVar by calculating the observed proportion of TLIC in temporal lobes meeting the specific dose constraints.

Results

RWDVar were significantly higher than RWDFix (p < 0.01). NTCP model performance was good (AUC:0.79-0.84). The median difference in estimated probability between RWDFix and RWDVar ranged between 5.3% and 20.0% points (p < 0.01), with V60GyRBE and DMax at the smallest and largest differences, respectively. The proportion of TLIC was higher for RWDFix (4.0%–13.1%) versus RWDVar (1.3%–5.3%). For V65GyRBE ≤ 0.03 cc the proportion of TLIC was less than 5% for both RWDFix and RWDVar.

Conclusion

NTCP estimates were significantly influenced by RBE variations. Dmax as model predictor resulted in the largest deviations in risk estimates between RWDFix and RWDVar. V65GyRBE ≤ 0.03 cc was the most consistent dose constraint for RWDFix and RWDVar.

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Published

2022-02-01

How to Cite

May Engeseth, G., Bolstad Hysing, L., Yepes, P., Seime Pettersen, H. E., Mohan, R., Dave Fuller, C., … Brandon Gunn, G. (2022). Impact of RBE variations on risk estimates of temporal lobe necrosis in patients treated with intensity-modulated proton therapy for head and neck cancer. Acta Oncologica, 61(2), 215–222. https://doi.org/10.1080/0284186X.2021.1979248

Issue

Vol. 61 No. 2 (2022): Acta Oncologica

Section

Articles