MicroRNAs as prognostic molecular signatures in human head and neck squamous cell carcinoma: a systematic review and meta-analysis.

The aim of this study was to systematically review the articles investigating the prognostic value of different microRNAs (miRs) in human head and neck squamous cell carcinoma (HNSCC). Following the guidelines of the Meta-analysis of Observational Studies in Epidemiology group (MOOSE), we performed a broad and sensitive search on online databases to identify the studies that examined associations between different miRs expression and HNSCC prognosis. In this study, we considered clinical endpoints such as overall survival (OS) and disease specific survival (DFS) as acceptable outcomes. The prognostic value was demonstrated using hazard ratio (HR) with 95% confidence interval (CI). A total of 21 studies involving 1685 subjects analyzed the relationship between miRNA and prognosis of HNSCC. Our findings showed that significant elevated expressions of miR-21, miR-18a, miR-134a, miR-210, miR-181a, miR-19a, and miR-155 were associated with poor survival in human HNSCC. Conversely, decreased expressions of miR-153, miR-200c, miR-363, miR-203, miR-17, miR-205, miR-Let-7d, Let-7g, miR-34a, miR-126a, miR-375, miR-491-p5, miR 218, miR-451 and miR-125b were associated with poor prognosis. Alteration in miR-193b expression level does not show any significant association with cancer survival. We performed meta-analysis on the articles choosing miR-21 as prognostic marker. After excluding the study causing heterogeneity, a fixed model was applied, which showed an association between increased expression of miR-21 and poor survival (Pooled HR=1.57-95% CI: 1.22-2.02, P<0.05). Based on the results, it can be concluded that miRs specifically miR-21 may be promising markers for prognosis prediction in HNSCC.