Prognostic value of perineural invasion in resected non-small cell lung cancer: A meta-analysis

Objective: The prognostic role of perineural invasion (PNI) in resected non-small cell lung cancer (NSCLC) remains unclear. A meta-analysis was performed to compare the overall survival (OS) of patients with resected NSCLC with and without PNI.Methods: The PubMed, EMBASE, and Web of Science databases were systematically searched to identify relevant studies investigating the effect of PNI on OS in patients with resected NSCLC. Pooled hazard ratio (HR) and 95% confidence intervals (CI) were estimated using a random-effects model. Separate meta-analyses using adjusted or unadjusted HR for OS were performed using Stata/SE 12.0.Results: Eleven studies comprising 2,279 patients were included. In total, PNI was identified in 9% (median, 4%-31%) of patients with resected NSCLC. The unadjusted pooled effect of the PNI was significantly associated with worse OS (HR, 2; 95% CI, 1.65-2.43). Adjusting for potential con-founders yielded a similar result, with OS being significantly worse (HR, 2.13; 95% CI, 1.8-2.51) for patients exhibiting PNI.Conclusion: This meta-analysis indicates that the PNI is a strong prognostic factor for unfavorable outcomes in patients with resected NSCLC. Further large-scale prospective lung cancer trials are required to validate these results.