Prognostic Role Of MiR-21 In Esophageal Cancer: A Meta-analysis

Objective: This meta-analysis was performed to synthetically evaluate the correlation between mi R-21 and the prognosis of esophageal cancer(EC) from all available studies, aiming to delineate the prognostic role of mi R-21 in EC.Methods: With proposed inclusion and exclusion criteria, we searched the electronic databases Pub Med,EMBASE, ISI Web of Science, Wan Fang Med Online, and China National Knowledge Infrastructure(CNKI) for observational studies analyzing the prognostic value of mi R-21 in EC. Relevant data were extracted from studies investigating the correlation between mi R-21 and survival in EC patients. The quality of included studies was also evaluated, and quality score was given to each study. Pooled hazard ratios(HRs), 95% CI and P value were applied to evaluate the relationship between mi R-21 expression and prognosis in EC. STATA v11.0 was used to conduct all the calculation, including pooled HR, 95% CI,heterogeneity test, sensitivity analysis, Egger’s test and funnel plot.Results: Two hundred and seventy-three studies for miR-21 and EC prognosis were identified from primary article search in Pubmed, Embase, Wan Fang Med Online, CNKI and Web of Science. After manually screening the abstracts, titles, key words and full texts, two hundred and sixty-six studies were excluded because they were review articles, case report, letters, polymorphism articles, laboratory studies or studies irrelevant to the current analysis. Totally 7 articles involving seven hundred and ninety-four patients were considered eligible for meta-analysis in this study according to the inclusion and exclusion criteria. Pooled HR suggested that high expression of mi R-21 was negative correlated with prognosis in EC patients(HR = 1.59,95%CI = 1.25-2.02,P = 0.001) and subgroup of esophageal squamous cell carcinoma(ESCC)(HR = 1.84,95%CI = 1.41-2.40,P = 0.001). The pooled HR in adenocarcinoma(AD) patients with high expression of mi R-21 was statistical insignificant(HR=0.82, 95%CI=0.47-1.44, P = 0.489).Conclusion: Elevated miR-21 has the potential to predict poor prognosis in ESCC, and is expected to become a new biomarker for the management of ESCC.