Lymph node ratio is a prognostic factor for non-small cell lung cancer

The lymph node ratio (LNR) is defined as the number of pathologically positive LNs divided by the number of LNs examined. Some studies reported that high LNR was significantly associated with poor survival of non-small cell lung cancer (NSCLC). However, other studies could not confirm this result. PubMed, Embase, and the Cochrane Register of Controlled Trials were searched for relevant studies published up to July 2015. Primary outcome was the relationship between LNR and disease-specific survival (DSS) and overall survival (OS). Twelve studies with 25138 NSCLC patients were included in this meta-analysis. Higher LNR was significantly associated with decreased OS (HR = 1.93; 95% CI 1.64 - 2.28; P < 0.00001) and DSS (HR = 1.82; 95% CI 1.55 - 2.14; P < 0.00001). In the subgroup analysis, N1 stage NSCLC patients with higher LNR also showed decreased OS (HR = 1.60; 95% CI 1.25 - 2.28; P = 0.0002) and DSS (HR = 1.82; 95% CI 1.55 - 2.21; P < 0.0001). This meta-analysis indicated that LNR was an independent predictor of survival in patients with NSCLC.