PV QA 4 - Poster Viewing Q&A 4
Purpose/Objective(s): Adjuvant chemotherapy is routinely offered following surgical resection for patients with early-stage non-small cell lung cancer (NSCLC) and tumors ≥4 cm; however, the role of adjuvant systemic therapy for patients managed with definitive stereotactic body radiotherapy (SBRT) has not been well defined. We investigated the association between receipt of adjuvant chemotherapy following SBRT and overall survival (OS) for patients with T1-T3N0 NSCLC in the National Cancer Database (NCDB).
Materials/Methods: The NCDB was queried for patients with T1-T3N0 NSCLC treated with definitive SBRT from 2004-2014. The association between receipt of adjuvant chemotherapy and OS was analyzed for the entire population (n=24,011) and a propensity-matched cohort (n=608) using Kaplan-Meier methods and Cox proportional hazard models. A subset analysis was also performed for patients with primary tumors ≥4 cm and concordant T-stage information (n=2,323).
Results: There were 24,011 patients meeting inclusion criteria with a median follow-up of 32.5 months. SBRT consisted of a median dose of 50 Gray delivered in a median of 4 fractions. A total of 322 patients (1.3%) received adjuvant chemotherapy given a median of 27 days after the start of SBRT (range: 1-56). Within the entire cohort, 5-year OS was 26.4% with adjuvant chemotherapy compared to 30.2% without adjuvant chemotherapy (p=0.001). On multivariate analysis, adjuvant chemotherapy was independently associated with increased overall mortality (hazard ratio:1.22, 95% confidence interval:1.06-1.40, p=0.005). For patients with tumors ≥4 cm, 5-year OS was 16.3% with adjuvant chemotherapy (n=80) compared to 18.64% without adjuvant chemotherapy (p=0.81). After propensity-score matching, an association between decreased OS and adjuvant chemotherapy persisted with those receiving adjuvant chemotherapy (n=322) having 5-year OS of 26.4% compared to 40.8% without adjuvant chemotherapy (p<0.0001).
Conclusion: Adjuvant chemotherapy following definitive SBRT for T1-3N0 NSCLC is associated with decreased OS and more specifically is not associated with a survival benefit for patients with tumors ≥4 cm.
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