The Prognostic Value of miR-21 and miR-155 in Non-small-cell Lung Cancer: A Meta-analysis

OBJECTIVE: miR-21 and miR-155 have been implicated in the prognosis of non-small-cell lung cancer, but the results are controversial. To resolve this issue, we performed a meta-analysis on miR-21 and miR-155 and non-small-cell lung cancer prognosis and lymphoid metastasis. METHODS: Eligible data were extracted and the correlation between miR-21 and miR-155 and non-small-cell lung cancer survival was analyzed by calculating a pooled hazard ratio and sensitivity analysis. The heterogeneity was detected by Q statistic and I-squared statistic, and the publication bias was tested by funnel plots and Egger's test. RESULTS: Nineteen studies were included. High miR-21 level (hazard ratio = 2.00, 95% confidence interval = 1.38-2.89, P = 0.000 for heterogeneity test, I(2) = 84.9%) and high miR-155 level (hazard ratio = 1.65, 95% confidence interval = 1.11-2.44, P = 0.004 for heterogeneity test, I(2) = 68.3%) were significantly associated with worse non-small-cell lung cancer survival. Furthermore, a high miR-21 level was associated with an increased risk of lymphoid infiltration for non-small-cell lung cancer (odds ratio = 1.93; 95% confidence interval = 1.31-2.85). Funnel plot and Egger's test suggested that there was no publication bias in the current meta-analysis. CONCLUSIONS: This meta-analysis provides evidence that miR-21 and miR-155 are predicting factors for non-small-cell lung cancer prognosis and lymphoid infiltration.