Survival outcomes in extensive stage small cell lung cancer patients treated with thoracic radiation.

Abstract

8565 Background: The benefit of consolidation thoracic radiation in extensive stage small cell lung cancer (E-SCLC) remains unclear. This study utilized the National Cancer Database (NCDB) to evaluate overall survival outcome (OS) for patients receiving chemotherapy (CT) alone for E-SCLC versus CT + thoracic radiation (TRT). Methods: The NCDB was queried to capture patients (pts) with stage E-SCLC from 2010-2013. Patients with brain metastases at diagnosis were excluded, as were patients receiving radiation prior to initiation of chemotherapy. Univariate association of OS was assessed using Cox proportional hazards models and log-rank tests. A multivariable Cox proportional hazard model and Kaplan-Meier analyses were performed to compare treatment with CT only to CT + TRT. Propensity score matching method was also implemented to reduce treatment selection bias. All analyses were performed using SAS Version 9.4. Results: A total of 14,367 (12,019 received CT, 2,348 received CT + TRT) pts were included in the analysis. Patient characteristics included a median age of 66 years; 66 years for pts receiving CT, and 63 for pts receiving CT + TRT (p < 0.001). Male gender comprised 51% of pts; 52% in CT group versus 49% in CT + TRT (p < 0.001). Charlson-Deyo comorbidity score was zero in 53% of all patients; 52% in the CT group versus 57% of CT + TRT group (p < 0.001). In the CT + TRT group, the median total thoracic radiation dose was 45 Gy. On multivariate analysis, CT only was associated with an increased risk of death relative to CT+ TRT (HR 1.74 [1.65 – 1.84], p < 0.001). 5 year OS was 7% vs. 2% for CT + TRT versus CT alone (p < 0.001). On propensity matched analysis, CT + TRT was associated with better 5-year OS compared to CT alone (8% vs. 2%; p < 0.001). On multivariate analysis of propensity matched samples, chemotherapy alone continued to be associated with worse survival (HR 1.76 [1.62 – 1.91], p < 0.001). Conclusions: For E-SCLC, CT alone as standard of care is associated with worse survival relative to CT + TRT.