Prognostic role of tissue and circulating microRNA-200c in malignant tumors: a systematic review and meta-analysis

Background: Recently, many studies have shown that microRNAs (miRNA) exhibit altered expression in various cancers and may serve as prognostic biomarkers. We performed a systematic review and meta-analysis to evaluate the prognostic role of miR-200c expression in different cancers. Methods: Studies were recruited by searching PubMed, Embase and the Cochrane Library (last search update was May 2014) and assessed by further quality evaluation. Results: A total of 25 studies dealing with various carcinomas were identified for systematic review. Among them, 18 studies were ultimately included in the meta-analysis. Our results indicated that the expression of tissue miR-200c was not associated with OS and PFS in various carcinomas; however, downregulation of tissue miR-200c did predict poor OS of patients with stage I disease (HR=0.41, 95% CI 0.25-0.68, P=0.001). Furthermore, overexpression of blood miR-200c was significantly related to poor OS and PFS (HR=3.07 95% CI 1.58-5.96 P=0.001, HR=2.26 95% CI 1.66-3.08 P