Radiotherapy improves the survival of patients with stage IV NSCLC: A propensity score matched analysis of the SEER database

OBJECTIVES: The survival advantage of radiotherapy (RT) for patients with stage IV non‐small cell lung cancer (NSCLC) has not been adequately evaluated. METHODS: We analyzed stage IV NSCLC patients enrolled from the Surveillance, Epidemiology, and End Results (SEER) registry through January 2010 to December 2012. Propensity score (PS) analysis with 1:1 nearest neighbor matching method was used to ensure well‐balanced characteristics of all comparison groups by histological types and metastatic sites. Kaplan‐Meier and Cox proportional hazardous model were used to evaluate the overall survival (OS), cancer‐specific survival (CSS), and corresponding 95% confidence interval (95%CI). RESULTS: Generally speaking, there was a trend toward improved OS and CSS for using RT to stage IV NSCLC patients for any metastatic sites and for any histological types except adenocarcinoma (AD). Radiotherapy significantly improved the survival of NSCLC patients with metastasis to brain (P < 0.001), especially for AD (P < 0.001). For stage IV lung cancer patients with squamous cell carcinoma (SQC), RT for any metastatic sites could universally improve the OS (P < 0.001) and CSS (P < 0.001). In particular, RT was also associated with improving OS (P < 0.001) and CSS (P = 0.012) for stage IV patients with metastases of two or more sites, ie, polymetastatic disease. Furthermore, for those stage IV SQC patients without metastasis, RT, most likely to the primary site, also significantly improved the survival (P < 0.001). CONCLUSIONS: The results support that RT might improve the survival of patients with metastatic NSCLC in a PS‐matched patient cohort from the large SEER database. It is prudent to carefully select patients for RT in metastatic NSCLC.