Association between event-free survival and overall survival after neoadjuvant treatment for non-small cell lung cancer: a systematic review and meta-analysis

BackgroundWe 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 methodsElectronic 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.ResultsWe 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).ConclusionsWe 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.