Cumulative rib fracture risk after stereotactic body radiotherapy in patients with localized non-small cell lung cancer.

Radiother Oncol

Department of Oncology, Odense University Hospital, Odense, Denmark; Department of Clinical Research, University of Southern Denmark, Odense, Denmark; Academy of Geriatric Cancer Research (AgeCare), Odense University Hospital, Odense, Denmark.

Published: November 2024

AI Article Synopsis

  • - This study investigates the risk of rib fractures in patients with localized non-small cell lung cancer (NSCLC) following stereotactic body radiotherapy (SBRT), examining both patient-related and dosimetric factors.
  • - Out of 602 patients analyzed, 19% experienced rib fractures, with significant risk factors including female gender, bone density, and specific dosimetric parameters like V20 and V30 to the rib.
  • - The findings indicate that while 19% of patients developed rib fractures, dosimetric parameters were more influential in predicting this risk than patient-related factors, highlighting the importance of treatment planning in SBRT.

Article Abstract

Introduction: Rib fracture is a known complication after stereotactic body radiotherapy (SBRT). Patient-related parameters are essential to provide patient-tailored risk estimation, however, their impact on rib fracture is less documented compared to dosimetric parameters. This study aimed to predict the risk of rib fractures in patients with localized non-small cell lung cancer (NSCLC) post-SBRT based on both patient-related and dosimetric parameters with death as a competing risk.

Materials And Methods: In total, 602 patients with localized NSCLC treated with SBRT between 2010-2020 at Odense University Hospital, Denmark were included. All patients received SBRT with 45-66 Gray (Gy)/3 fractions. Rib fractures were identified in CT-scans using a word embedding model. The cumulative incidence function was based on cause-specific Cox hazard models with variable selection based on cross-validation model likelihood performed using 50 bootstraps.

Results: In total, 19 % of patients experienced a rib fracture. The cumulative risk of rib fracture increased rapidly from 6-54 months post-SBRT. Female gender, bone density, near max dose to the rib, V30 and V40 to the rib, gross tumor volume, and mean lung dose were significantly associated with rib fracture risk in univariable analysis. The final multi-variable model consisted of V20 and V30 to the rib and mean lung dose.

Conclusion: Female gender and low bone density in male patients are significant predictors of rib fracture risk. The final model predicting cumulative rib fracture risk of 19 % in patients with localized NSCLC treated with SBRT contained no patient-related parameters, suggesting that dosimetric parameters are the primary drivers.

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Source
http://dx.doi.org/10.1016/j.radonc.2024.110481DOI Listing

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