Prognostic significance of the neutrophil to lymphocyte ratio in patients with non-small cell lung cancer: a systemic review and meta-analysis

Neutrophil to Lymphocyte Ratio (NLR) was recently demonstrated as a useful index in predicting the prognosis of Non-Small Cell Lung Cancer (NSCLC). Thus, a meta-analysis was performed to demonstrate the relationship between NLR and overall survival (OS), progress-free survival (PFS) or disease free survival (DFS) in patients with NSCLC. We searched for relevant literatures in PubMed, EMBASE and Cochrane library and pooled the eligible studies and synthesized hazard ratios (HRs) using Stata 12.0. Final analysis of NSCLC patients from 12 eligible studies was performed. Combined HR suggested that high NLR had an unfavorable effect on patients' OS (n=1700 in 11 studies; HR=1.43, 95% CI: 1.25-1.64; I<^>2=80.2%, P<0.01) and PFS (n=664 in 5 studies, HR=1.37, 95% CI: 1.07-1.74; I<^>2=70.8%, P=0.004). Subgroup analysis based on cutoff shown that, compared with other subgroups, the subgroup with a cutoff of 5 had a significantly poorer survival (HR=1.87, 95% CI 1.49-2.34) with less heterogeneity (I<^>2=21.3%, P=0.28). However, subgroup analysis based on treatment method indicated that the "surgery" subgroup seemed to have not a significant impact on survival (HR=1.32, 95% CI 0.99-1.77; I<^>2=80.0%, P=0.063) compared with the chemotherapy subgroup (HR=1.61, 95% CI 1.24-2.10; I<^>2=82.6%, P<0.01). Additionally, combined odds ratio (OR) suggested high NLR was associated inversely with response to treatment (n = 276 in 2 studies; OR = 1.73, 95% CI: 1.04-2.88; I<^>2=0%, P=0.40). This study suggests high NLR (especially with a cutoff of 5) seems to be associated with a worse prognosis in patients with NSCLC as well as a worse response to treatments.