Abstract
BackgroundStereotactic ablative volume reduction (SAVR) is a potential alternative to lung-volume reduction surgery in patients with severe emphysema and excessive surgical risk. Having previously observed a dose-volume response for localized lobar volume reduction after stereotactic ablative radiotherapy (SABR) for lung tumors, we investigated the time course and factors associated with volume reduction.MethodsWe retrospectively identified 70 eligible patients receiving lung tumor SABR during 2007-2013. We correlated lobar volume reduction (relative to total, bilateral lung volume [TLV]) with volume receiving high biologically effective doses (VXXBED3) and other pre-treatment factors in all patients, and measured the time course of volume changes on 3-month interval CT scans in patients with large V60BED3 (n = 21, V60BED3 ≥4.1 % TLV).ResultsMedian CT follow-up was 15 months. Median volume reduction of treated lobes was 4.5 % of TLV (range 0.01–13.0 %), or ~9 % of ipsilateral lung volume (ILV); median expansion of non-target adjacent lobes was 2.2 % TLV (−4.6–9.9 %; ~4 % ILV). Treated lobe volume reduction was significantly greater with larger VXXBED3 (XX = 20–100 Gy, R2 = 0.52–0.55, p < 0.0001) and smaller with lower pre-treatment FEV1% (R2 = 0.11, p = 0.005) in a multivariable linear model. Maximum volume reduction was reached by ~12 months and persisted.ConclusionsWe identified a multivariable model for lobar volume reduction after SABR incorporating dose-volume and pre-treatment FEV1% and characterized its time course.Electronic supplementary materialThe online version of this article (doi:10.1186/s13014-016-0616-8) contains supplementary material, which is available to authorized users.
Highlights
Stereotactic ablative volume reduction (SAVR) is a potential alternative to lung-volume reduction surgery in patients with severe emphysema and excessive surgical risk
Having observed in our practices lung parenchymal scarring and tissue contraction following lung tumor stereotactic ablative radiotherapy (SABR), we hypothesized that SABR might, as a secondary effect of tumor treatment, achieve volume reduction (stereotactic ablative volume reduction, (SAVR))
After previously identifying a dose–response relationship for treated lobe volume reduction following lung tumor SABR [12], we evaluated the time course of volume reduction and predictive pretreatment factors in a larger patient cohort
Summary
Stereotactic ablative volume reduction (SAVR) is a potential alternative to lung-volume reduction surgery in patients with severe emphysema and excessive surgical risk. Having previously observed a dose-volume response for localized lobar volume reduction after stereotactic ablative radiotherapy (SABR) for lung tumors, we investigated the time course and factors associated with volume reduction. As demonstrated by the National Emphysema Treatment Trial (NETT), lung-volume-reduction surgery (LVRS) improved quality of life, exercise tolerance, pulmonary function in select patients, and increased survival for a subset with low exercise capacity and upper lobe-. Having observed in our practices lung parenchymal scarring and tissue contraction following lung tumor SABR, we hypothesized that SABR might, as a secondary effect of tumor treatment, achieve volume reduction (stereotactic ablative volume reduction, (SAVR)). If we can establish that this occurs, our longerterm goal will be to develop this into a potentially less morbid means of creating therapeutic lung volume reduction in emphysema patients
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