Neutrophil-to-Lymphocyte Ratio Predicts PSA Response and Prognosis in Prostate Cancer: A Systematic Review and Meta-Analysis

An unprecedented advance has been seen in castration-resistant prostate cancer (CRPC) treatments in the past few years. With a number of novel agents were approved, there is a pressing need to develop improved prognostic biomarkers to facilitate the personalised selection and sequencing of these novel agents. Emerging evidence indicates that the neutrophil-to-lymphocyte ratio (NLR) is associated with poorer survival in patients with prostate cancer (PCa). However, the importance of the NLR for the prediction of the PSA response (PSARS) and biochemical recurrence (BCR) has been largely neglected. Here, we conducted a systematic review and meta-analysis to evaluate the prognostic value of the NLR for the PSARS, BCR, and survival in PCa. A systematic database search was performed using Embase, PubMed, the Cochrane Library, and the China National Knowledge Infrastructure (CNKI). A meta-analysis was performed by pooling hazard ratios (HRs), odds ratios (ORs) and the corresponding 95% confidence intervals (CIs). A total of 22 studies were included in the meta-analysis. Our results suggest that an elevated NLR predicts a lower PSARS rate (OR = 1.69, 95% CI: 1.40-1.98) and a higher possibility of BCR (HR = 1.12, 95% CI: 1.02-1.21). Additionally, we confirmed that an elevated NLR was a prognostic predictor of shorter overall survival (OS) in both metastatic castration-resistant PCa (mCRPC) (HR = 1.45, 95% CI: 1.32-1.59) and localized PCa (LPC) (HR = 1.12, 95% CI: 1.01-1.23) and that it predicted worse progression-free survival (PFS) in CRPC (HR = 1.42, 95% CI: 1.23-1.61) and poorer recurrence-free survival (RFS) (HR = 1.38, 95%CI: 1.01-1.75) in LPC. Our results suggest that an elevated NLR might be employed as a prognostic marker of biochemical changes and prognosis to facilitate risk stratification and decision making for individual treatment of PCa patients. The potential mechanisms underlying these associations and future research directions are also discussed.