Prognostic role of neutrophil to lymphocyte ratio in lung cancers: a meta-analysis including 7,054 patients

Background: Neutrophil to lymphocyte ratio (NLR) has recently been reported to be a poor prognostic indicator in lung cancer. However, the prognostic value of the NLR in patients with lung cancer still remains controversial. We performed a meta-analysis to evaluate the prognostic value of NLR in patients with lung cancer. Methods: We performed a comprehensive literature search in PubMed, Ovid, the Cochrane Library, and Web of Science databases in May 2015. Studies were assessed for quality using the Newcastle-Ottawa Scale. Results: Twenty-two studies with a total of 7,054 patients were included in this meta-analysis. The meta-analysis was performed to generate combined hazard ratios (HRs) for overall survival (OS) and progression-free survival (PFS). Our analysis results indicated that high NLR predicted poorer OS (HR, 1.51; 95% confidence interval [CI], 1.33-1.71; P < 0.001) and PFS (HR, 1.33; 95% CI, 1.07-1.67; P = 0.012) in patients with lung cancer. High NLR was also associated with poor OS in lung cancer treated by surgical resection (HR, 1.59; 95% CI, 1.26-1.99; P < 0.001) and chemotherapy (HR, 1.15; 95% CI, 1.08-1.22; P < 0.001). In addition, NLR cut-off value = 5 (HR, 1.57; 95% CI, 1.16-2.12; P = 0.003) and NLR cut-off value <5 (HR, 1.47; 95% CI, 1.28-1.69; P < 0.001). Conclusion: This meta-analysis result suggested that NLR should have significant predictive ability for estimating OS and PFS in patients with lung cancer and may be as a significant biomarker in the prognosis of lung cancer.