Clinical Outcomes of Stereotactic Body Radiation Therapy across Treatment Platforms Employing Varied Approaches to Respiratory Management at a Single Institution

Abstract

<h3>Purpose/Objective(s)</h3> Stereotactic Body Radiation Therapy (SBRT) has been the standard of care for early-stage non-small cell lung cancer patients who do not undergo surgery since soon after the publication of RTOG 0236. Since then, various linear accelerator platforms have been employed with a variety of approaches to respiratory management, treatment planning and treatment delivery. Comparisons of local control and survival end points using a variety of treatment platforms in addition to respiratory management techniques have not been reported. Here, we present the results of our analysis of clinical outcomes at a single institution across multiple treatment platforms representative of the available technology since the widespread adoption of SBRT for early-stage lung cancer. <h3>Materials/Methods</h3> Consecutive patients who underwent SBRT for early-stage lung cancer between 2011 and 2018 at a single institution were retrospectively analyzed. Treatments were planned and delivered with standardized simulation, dose and fractionation per institutional guidelines. Overall Survival (OS), Local Control (LC), Distant Metastasis Free Survival (DMFS), and Progression Free Survival (PFS) were calculated for the entire cohort. Log rank comparisons of all survival endpoints were then calculated by treatment platform: stereoscopic orthogonal kV x-ray localization with conventional Linac (Linac1), volumetric cone beam CT localization with conventional Linac (Linac2), and megavoltage CT with helical tomotherapy (Linac3). Comparisons were also performed by respiratory management technique: free breath (FB), breath hold (BH) or end expiration respiratory gating (RG). <h3>Results</h3> A total of 240 patients were included in the analysis. Treatment platform utilization was well balanced in the group: 28% on Linac1, 32% on Linac2, and 40% on Linac3. The majority of patients were treated with FB, 72%. Median OS for the entire cohort was 50 months. The crude rate of local recurrence was 7%. Kaplan-Meier estimate of LC for the entire cohort was 94% at 3 years. The median time to local recurrence was not reached. LC was not impacted by treatment platform, p = 0.897, or respiratory management technique, p = 0.623. Comparisons by treatment platform and respiratory management technique revealed no significant differences in OS, DMFS, and PFS. <h3>Conclusion</h3> Irrespective of treatment platform or approach to respiratory management, SBRT remains highly effective at providing durable LC in patients with early-stage lung cancer. Differences in treatment delivery platform and respiratory management do not significantly influence other disease control and survival outcomes.