Impact of Facility Treatment Volume on Stereotactic Ablative Radiotherapy (SABR) Outcomes in Early-Stage Non-Small Cell Lung Cancer (NSCLC).

Prior research suggests that radiation oncologist provider experience may influence outcomes for radiation treatment modalities requiring greater technical expertise for given disease sites. We investigated whether institution treatment volume (TV) for SABR technique impacted survival outcomes for patients with NSCLC.We conducted a retrospective cohort study using the Veteran's Affairs Informatics and Computing Infrastructure (VINCI) database to identify patients who underwent treatment for NSCLC between 2012 and 2017 at Veteran's Health Administration Medical Centers (VHAMCs). Patients were included in the cohort if they had tumor (T) stage 1 or 2 disease, node negative (N0) disease, and underwent SABR radiation treatment based on associated Current Procedural Terminology codes. We conducted univariate and multivariate analyses for overall survival (OS) and cause-specific survival (CSS) using Cox regression models accounting for age, sex, race, histology, T stage, tobacco history, ECOG status, and VHAMC facility TV. TV was calculated as the total number of SABR treatments performed per facility over the study period and was categorized into high and low volume groups based on a median TV cutoff.The observational cohort included N = 433 patients with early-stage NSCLC who underwent treatment with SABR across 25 VHAMC facilities. Most patients (83.1%) had T stage 1 disease, and nearly equal proportions had SCC (31.2%) and adenocarcinoma (32.5%) histologies, with the remaining having clinical diagnoses of NSCLC. Median facility TV was 29 SABR treatments (interquartile range 19-33). Median follow up was 657 days. Estimated 2-year overall and cause-specific survival rates were 78.4% (95% CI: 73.9% - 82.1%) and 87.0% (95% CI: 83.2% - 90.0%), respectively. On univariate analysis, high versus low facility TV was not significantly associated with OS (hazard ratio (HR) 1.08, 95% CI: 0.74-1.58) or CSS (HR 1.06, 95% CI: 0.65 - 1.73). Similarly, facility volume was not associated with OS or CSS on multivariate analysis. In a sensitivity analysis, facility volume was not associated with survival outcomes when treated as a continuous variable. Covariates associated with decreased OS included male sex (HR 4.5, P < 0.05), age over 65 (HR 1.77, P < 0.05), ECOG status 2 or greater (HR 1.94, P < 0.05), SCC histology (HR 1.66, P < 0.05), and T stage 2 disease (HR 1.68, P < 0.05).In this observational cohort of patients treated at VHAMCs, facility TV was not associated with survival outcomes for early-stage NSCLC radiation treatment using SABR technique. Research is ongoing to account for factors including baseline pulmonary function, comorbidities, and variations in institutional treatment patterns such as propensity for treatment with surgery versus radiation.

Duke Scholars

Author Vinit Nalawade