Radiotherapy improves the survival of patients with extensive-disease small-cell lung cancer: a propensity score matched analysis of Surveillance, Epidemiology, and End Results database

Rui Zhang,* Ping Li,* Qin Li, Yunfeng Qiao, Tangpeng Xu, Peng Ruan, Qibin Song, Zhenming Fu Cancer Center, Renmin Hospital of Wuhan University, Wuhan 430060, China *These authors contributed equally to this work Background: The survival advantage of radiotherapy for patients with extensive-disease small-cell lung cancer (ED-SCLC) has not been adequately evaluated.Methods: We analyzed stage IV SCLC patients enrolled from the Surveillance, Epidemiology, and End Results (SEER) registry through January 2010 and December 2012. Propensity score analysis with 1:1 matching was performed to ensure well-balanced characteristics of all comparison groups. Kaplan–Meier and Cox proportional hazardous model were used to evaluate the overall survival (OS), cancer-specific survival (CSS), and corresponding 95% CI.Results: Overall, for all metastatic ED-SCLC, receiving radiotherapy was associated with both improved OS and CSS. Radiotherapy for thoracic lesion and any metastatic sites could significantly improve the OS and CSS, except for brain metastasis. For M1a-SCLC patient, radiotherapy, most likely to the primary site, significantly improved the survival (P<0.001). Furthermore, for those ED-SCLC patients with ≥ 2 metastatic sites, that is, polymetastatic ED-SCLC patients, radiation also significantly improved the median OS from 6.0 to 8.0 months (P=0.015) and the median CSS from 7.0 to 8.0 months (P=0.020).Conclusion: The large SEER results support that radiotherapy in addition to chemotherapy might improve the survival of patients with metastatic ED-SCLC. Keywords: small-cell lung cancer, radiotherapy, extensive disease, metastasis, propensity score matc