Consecutive Daily vs. Every Other Day SBRT Scheduling for Stage I NSCLC

Abstract

<h3>Purpose/Objective(s)</h3> The optimal delivery schedule for stereotactic body radiation therapy (SBRT) in treating Stage I non-small cell lung cancer (NSCLC) is unknown. This study utilized the National Cancer Database (NCDB) to examine daily vs. every other day (QOD) SBRT scheduling in the United States, including trends over time and association with survival. <h3>Materials/Methods</h3> The NCDB was used to identify patients with Stage I NSCLC treated with 3, 4, or 5 fraction SBRT between 2004-2016. Daily scheduling was defined as completing SBRT in 3, 4, or 5 days, respectively. QOD scheduling for 3, 4, and 5 fractions was defined as SBRT completion in 5-9, 8-12, and 10-14 days, respectively. Survival analysis was performed using the Kaplan-Meier method and Cox regression modeling. The multivariate model included age, gender, race, insurance status, median income, Charlson-Deyo comorbidity score, clinical T stage, histology, and facility type. <h3>Results</h3> Of 15,269 patients who met study criteria, 3,927 (25.7%) received SBRT daily, and 11,342 (74.3%) received treatment QOD. A total of 4,993 (32.7%), 4,278 (28.0%), and 5,998 (39.3%) patients received 3, 4, and 5 fractions, respectively. The most common dose fractionations were 10 Gy x 5 (26.7%), 12 Gy x 4 (18.4%), and 18 Gy x 3 (17.3%). Factors significantly associated with daily SBRT scheduling included lower income (<i>P</i> < 0.0001), lower comorbidities (<i>P</i> = 0.0019), and treatment at academic/research programs (<i>P</i> < 0.0001). The use of daily SBRT scheduling decreased from a peak of 36.8% in 2007 to 21.7% in 2016, while QOD treatment increased from a nadir of 63.2% in 2007 to 78.3% in 2016 (both <i>P</i> < 0.0001). The use of 3-fraction SBRT decreased over time from 81.5% in 2004 to 23.4% in 2016, while 5-fraction SBRT increased from 3.7% in 2004 to 51.4% in 2016 (both <i>P</i> < 0.0001); there was no significant change in use of 4-fraction regimens (<i>P</i> = 0.6). The most common treatment schedule was 3 fractions QOD from 2004-2011 (25.5-70.4%), while more recently 5 fractions QOD was most prevalent from 2012-2016 (rising from 28.5% in 2012 to 41.6% in 2016). Median follow-up was 28.9 months, and median survival was 38.3 months. Median survival for patients who received daily SBRT was 37.9 months vs. 38.4 months for QOD (<i>P</i> = 0.4). On multivariate analysis, no difference was found in overall survival between daily vs. QOD scheduling (hazard ratio [HR] 0.99 [95% confidence interval 0.94-1.04]; <i>P</i> = 0.6). With 3-fraction SBRT, QOD treatment was associated with improved survival vs. daily treatment (HR 0.91 [0.84-0.98]; <i>P</i> = 0.02). With 5-fraction SBRT, QOD treatment was associated with worse survival vs. daily treatment (HR 1.11 [1.02-1.22]; <i>P</i> = 0.02). <h3>Conclusion</h3> In this NCDB analysis, QOD SBRT schedules were more frequently used to treat Stage I NSCLC than daily regimens by a factor of 3:1. QOD scheduling increased over time, as did 5-fraction treatments, with 5-fraction QOD becoming the most common dose schedule after 2012. No clear association was found between daily vs. QOD scheduling and overall survival.