A meta-analysis on the prognosis of exosomal miRNAs in all solid tumor patients

Background: It has been reported that the encapsulated miRNAs from exosomes are potential biomarkers of tumors prognosis. Yet, the results are controversial, so it is obliged to do a meta-analysis to reach a definite conclusion. Materials and methods: Studies were searched for published in PubMed, Embase, and Web of Science databases until April 20, 2018. A meta-analysis was conducted to appraise the role of exosomal miRNAs in prognosis of cancer patients. Results: The different exosomal miRNAs expression was remarkably related to overall survival (OS) (hazard ratio [HR]=2.02, 95% confidence interval [CI]: 1.84-2.21) and disease-free survival (DFS) (HR=2.43, 95% CI: 1.86-3.17) of cancer patients. High exosomal miR-21 expression was associated with poor OS (HR=2.59; 95% CI: 1.71-3.90) and DFS (HR=1.84; 95% CI: 1.37-2.47). High exosomal miR-451a expression was associated with poor OS (HR=4.81; 95% CI: 2.33-9.93) and DFS (HR=2.64; 95% CI: 1.62-4.31). High exosomal miR-1290 expression was associated with poor OS (HR=1.73; 95% CI: 1.29-2.33). Low exosomal miR-638 expression was associated with poor OS (HR=2.25; 95% CI: 1.46-3.46). Conclusion: The expression levels of exosomal miRNAs, particularly miR-21, miR-451a, miR-1290, and miR-638 could strongly predict prognosis of solid tumor patients and might be a potential target for tumor treatment.