Survival Outcomes With Thoracic Radiotherapy in Extensive-Stage Small-Cell Lung Cancer: A Propensity Score-Matched Analysis of the National Cancer Database

Background: The prognosis of patients with extensive-stage small-cell lung carcinoma (ES-SCLC) is poor. The benefit of consolidative thoracic radiation therapy (TRT) in ES-SCLC has been inconclusive, and its use inconsistent. The objective of this study was to evaluate overall survival (OS) of ES-SCLC patients treated with chemotherapy (CT) with or without TRT using an administrative database approach. Patients and Methods: The National Cancer Database was queried to identify patients with ES-SCLC diagnosed between 2010 and 2014. Those with brain metastases, those who received radiotherapy before CT, or radiotherapy outside the thorax, were excluded. Propensity score-matching (PSM) was used to compare OS of patients treated with CT and TRT with those who received CT alone. Patients who received >10 radiotherapy fractions were also compared with those who received 10 or fewer. Results: We included 14,367 patients in the primary analysis; 12,019 received CT alone, and 2348 received CT with TRT. In multivariate analysis, CT was associated with an increased risk of death relative to CT with TRT (hazard ratio [HR], 1.74 [95% confidence interval (CI), 1.64-1.84]; log-rank P < .001), which remained significant with PSM. Median OS was 12.1 versus 8.2 months (CT with TRT vs. CT); 12-month OS was 50.5% versus 28.5%, and 5-year OS 7.6% versus 2.0% (HR, 1.80 [95% CI, 1.67-1.95], HR P < .001). Of 3099 patients who received TRT, >10 radiotherapy fractions was associated with superior OS (HR, 1.70 [95% CI, 1.49-1.95], log-rank P < .001); this finding remained significant with PSM. Conclusion: Use of TRT after CT in ES-SCLC patients was associated with long-term survival; its use should be considered in addition to standard of care CT.