Background: We wanted to evaluate if event-free survival (EFS) is a reliable surrogate for overall survival (OS) in patients with resectable non-small cell lung cancer (r-NSCLC) receiving neoadjuvant therapy. We conducted a systematic literature review and meta-analysis to investigate the statistical association between EFS and OS.
Research design and methods: Electronic databases were searched on 30 July 2021 to identify sources reporting both EFS and OS data in patients with stage I-IIIB r-NSCLC receiving neoadjuvant therapy. Correlation and regression analyses evaluated the association between the effect of treatment on EFS and OS using log-hazard ratios (HRs). Sources in which the entire population had epidermal growth factor receptor mutations were excluded from the analyses.
Results: We identified 74 sources, of which 8 reported EFS and OS HRs from randomized controlled trials. Based on these, we found a positive linear correlation and a strong association between EFS and OS log-HRs (weighted Pearson's correlation coefficient r = 0.864; 95% confidence interval 0.809-0.992; P = 0.006; random-effects meta-regression, R2 = 0.777).
Conclusions: We found a strong association between treatment effects for EFS and OS, indicating that improvements in EFS are likely to be predictive of improvements in OS. EFS may therefore be a reliable surrogate for OS after neoadjuvant therapy in r-NSCLC.
Keywords: Event-free survival; neoadjuvant therapy; overall survival; resectable non-small cell lung cancer; surrogate endpoint.