Circulating MicroRNAs as Prognostic Molecular Biomarkers in Human Head and Neck Cancer: A Systematic Review and Meta-Analysis

Background. Circulating microRNAs (miRNAs) are potential molecular biomarkers for cancer detection; however, little is known about their prognostic role in head and neck cancer. This current study is aimed at evaluating the role of novel miRNAs in the survival of head and neck cancer patients. Materials and Methods. We performed a systematic literature search using online databases for articles published between December 2006 and February 2019. A meta-analysis was conducted to assess the correlation between miRNA expressions and overall survival (OS) among the selected head and neck cancer studies. After multilevel screening by reviewers, meta-analysis was performed using hazard ratios (HR) and associated 95% confidence interval (CI) of survival to calculate a pooled effect size. Result. A total of 1577 patients across 13 studies were included in the literature review, with 18 miRNAs upregulated and 4 miRNAs downregulated predicting a poor overall survival. The forest plot generated using cumulated survival data resulted in a pooled HR value of 2.943 (95% CI: 2.394-3.618) indicating a strong association of dysregulated miRNA expression with a poor outcome. Only 2 miRNAs-low levels of miR-9 and high levels of miR-483-5p-were observed in two studies, both showing a significant association with overall cancer survival. Conclusion. To our knowledge, this is the first comprehensive systematic review and meta-analysis that examines the prognostic role of circulating miRNAs from blood in head and neck cancer patients. The combined effect estimates a HR across multiple studies and also supports the previous individual findings that an alteration in miRNA expression is highly associated with poor prognosis. This has the potential to use serum and/or plasma miRNAs as biomarkers and become novel tools for predicting the prognosis of head and neck cancer patients in the near future.