Prognostic role of platelet to lymphocyte ratio in non-small cell lung cancers: A meta-analysis including 3,720 patients.

Platelet to lymphocyte ratio (PLR) was recently reported as a useful index in predicting the prognosis of lung cancer. However, the prognostic role of PLR in lung cancer remains controversial. The aim of this study was to evaluate the association between PLR and clinical outcome of lung cancer patients through a meta-analysis. Relevant literatures were retrieved from PubMed, Ovid, the Cochrane Library and Web of Science databases. Meta-analysis was performed using hazard ratio (HR) and 95% confidence intervals (CIs) as effect measures. A total of 5,314 patients from 13 studies were finally enrolled in the meta-analysis. The summary results showed that elevated PLR predicted poorer overall survival (OS) (HR: 1.526, 95%CI: 1.268-1.836, p < 0.001) in patients with lung cancer and OS (HR: 1.631, 95%CI: 1.447-1.837, p < 0.001) in patients with nonsmall cell lung cancer (NSCLC). Subgroup analysis revealed that increased PLR was also associated with poor OS in NSCLC treated by surgical resection (HR: 1.884, 95%CI: 1.308-2.714, P < 0.001) and non-surgery (HR: 1.570, 95%CI: 1.323-1.863, P < 0.001). In addition, PLR Cut-off value ≤ 160 (HR: 1.506, 95%CI: 1.292-1.756, P < 0.001) and PLR Cut-off value>160 (HR: 1.842, 95%CI: 1.523-2.228, P < 0.001). In contrast, elevated PLR was not associated with OS (HR: 1.117, 95%CI: 0.796-1.569, P > 0.05) in patients with small cell lung cancer (SCLC).This meta-analysis result suggested that elevated PLR might be a predicative factor of poor prognosis for NSCLC patients.