Prognostic significance of circulating microRNA-21 expression in esophageal, pancreatic and colorectal cancers; a systematic review and meta-analysis

Literature has shown that aberrantly expressed microRNAs may have implications in certain cancers. A wealth of studies signal potential prognostic role of microRNA-21 in GIT cancers. This meta-analysis quantitatively determines prognostic significance of circulating microRNA-21 in esophageal squamous cell carcinoma (ESCC), pancreatic ductal adenocarcinoma (PDAC) and colorectal carcinoma (CRC). Databases of Medline, Wiley online library, Cochrane library, Taylor and Francis Online, CINAHL, Springer, Proquest, ISI Web of knowledge, ScienceDirect, and Emerald were searched using MeSH terms serum/tissue microRNA-21, prognosis, esophagus squamous cell carcinoma, pancreatic ductal adenocarcinoma, colorectal cancer. A systematic algorithm was used that selected 15 relevant studies. Meta-analysis was conducted using forest plot and a summary effect model was employed. This meta-analysis reports significant prognostic value of miR-21 in predicting worse overall survival (OS) in ESCC, PDAC, and CRC with pooled hazard ratio (HR) of 3.49 (95% CI 2.58–4.71, p -value < 0.01). Subgroup analysis for ESCC showed a pooled HR of 3.46 (95% CI 1.88–635, p value of <0.01), worse overall survival (OS) with the pooled HR of 3.14 (95% CI 2.22–4.43, p value < 0.01) for CRC and a pooled HR of 3.77 (95% CI 1.63–8.73, p value < 0.01) for PDAC. This research infers that microRNA-21 expression is a powerful prognostic tool. Expression of micro-RNA-21 is associated with poor OS and poorer disease-free survival in ESCC, PDAC and CRC. • Aberrant expression of microRNA-21 promotes carcinogenesis. • Predictive value of microRNA-21 expression to determine GIT cancers prognosis is not clear. • This research provides quantitative evidence that microRNA-21 expression predicts prognosis in the esophageal, pancreatic and colorectal cancers. • Micro-RNA-21 expression is associated with poor overall survival that can predict response to chemotherapy.