Key result
Photon radiotherapy was associated with significantly greater radiation-induced inflammation in the ascending aorta (15.8% vs 1.9% increase, p=0.043) and aortic arch (15.5% vs 1.3% increase, p=0.015) compared to proton radiotherapy.
Why the study?
To assess radiation therapy-induced vasculitis in non-small cell lung cancer patients by examining changes in aortic [18F]FDG uptake on PET/CT before and after proton versus photon radiotherapy.
Does proton radiotherapy reduce radiation-induced aortic inflammation compared to photon radiotherapy in patients with locally advanced NSCLC?
Cohort (n=35)
No
Does proton radiotherapy reduce radiation-induced aortic inflammation compared to photon radiotherapy in patients with locally advanced NSCLC?
Absolute Event Rate: 15.8% vs 1.9%
p-value: p=0.043
Proton radiotherapy may cause significantly less radiation-induced aortic inflammation than photon radiotherapy in patients with non-small cell lung cancer.
Photon RT linked to greater aortic inflammation than proton in NSCLC; leaves open whether protons reduce vascular risk in larger cohorts.
Purpose To assess radiation therapy (RT)-induced vasculitis in patients with non-small cell lung cancer (NSCLC) by examining changes in the uptake of 18F-fluoro-D-deoxyglucose ([18F]FDG) by positron emission tomography/computed tomography (PET/CT) images of the ascending aorta (AA), descending aorta (DA), and aortic arch (AoA) before and after proton and photon RT. Method Thirty-five consecutive locally advanced NSCLC patients were definitively treated with proton (n = 27) or photon (n = 8) RT and concurrent chemotherapy. The patients were prospectively enrolled to undergo [18F]FDG-PET/CT imaging before and 3 months after RT. An adaptive contrast-oriented thresholding algorithm was applied to generate mean standardized uptake values (SUVmean) for regions of interest (ROIs) 3 mm outside and 3 mm inside the outer perimeter of the AA, DA, and AoA. These ROIs were employed to exclusively select the aortic wall and remove the influence of blood pool activity. SUVmeans before and after RT were compared using two-tailed paired t-tests. Results RT treatments were associated with increased SUVmeans in the AA, DA, and AoA—1.9%, 0.3%, and 1.3% for proton and 15.8%, 9.5%, and 15.5% for photon, respectively. There was a statistically significant difference in the ∆SUVmean (post-RT SUVmean − pre-RT SUVmean) in patients treated with photon RT when compared to ∆SUVmean in patients treated with proton RT in the AA (p = 0.043) and AoA (p = 0.015). There was an average increase in SUVmean that was related to dose for photon patients (across structures), but that was not seen for proton patients, although the increase was not statistically significant. Conclusion Our results suggest that patients treated with photon RT for NSCLC may exhibit significantly more RT-induced inflammation (measured as ∆SUVmean) in the AA and AoA when compared to patients who received proton RT. Knowledge gained from further analyses in larger cohorts could aid in treatment planning and help prevent the significant morbidity and mortality associated with RT-induced vascular complications. Trial registration NCT02135679.
No takes yet. Share an insight, caveat, or question.
Evanson et al. (2023) conducted a cohort in Locally advanced non-small cell lung cancer (NSCLC) (n=35). Photon radiotherapy vs. Proton radiotherapy was evaluated on Change in mean standardized uptake value (∆SUVmean) in the ascending aorta (p=0.043). Photon radiotherapy was associated with significantly greater radiation-induced inflammation in the ascending aorta (15.8% vs 1.9% increase, p=0.043) and aortic arch (15.5% vs 1.3% increase, p=0.015) compared to proton radiotherapy.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: