Prognostic value of exosomal noncoding RNA in hepatocellular carcinoma: a meta-analysis.

High morbidity, recurrence and mortality make hepatocellular carcinoma (HCC) a leading cause of cancer-related burden and deaths. The lack of prognostic evaluation methods weakened the therapeutic efficacy for HCC. Exosomal noncoding RNAs (ncRNAs) play a key role in cancer development. Our meta-analysis aimed to assess the prognostic value of exosome-transferred noncoding RNAs in predicting the outcomes of patients with HCC. We obtained 16 articles from PubMed, Web of Science, Scopus, and EMBASE up to 4 November 2021. The ncRNAs were divided into three parts: microRNAs (miRNA), long noncoding RNAs (lncRNA), and circular RNAs (circRNA). In the pooled hazard ratios (HRs), upregulated miRNAs were 3.06 (95% CI = 2.51-3.73), downregulated miRNAs were 3.28 (95% CI = 2.61-4.11), lncRNAs were 3.34 (95% CI = 1.87-5.96), and circRNAs were 1.76 (95% CI = 1.36-2.14). As the results of subgroup analysis, upregulated miRNAs had a pooled HR of 3.10 (95% CI = 1.66-5.81), and the HR of downregulated miRNAs was 3.04 (95% CI = 2.17-4.28) for multivariate analysis of overall survival (OS). Meanwhile, upregulated miRNAs had a pooled HR of 2.61 (95% CI = 1.89-3.60), and the HR of downregulated miRNAs was 3.77 (95% CI = 1.11-12.73) for multivariate analysis of other endpoints. Remarkably, miR-21 has a pooled HR of 2.48 (95%CI = 1.52-4.05, I2 = 0) for disease-free survival (DFS). In conclusion, the expression of exosomal noncoding RNAs can be used to evaluate the prognosis of patients with HCC. Exosome-transferred miR-21 might serve as a potential prognostic biomarker in HCC.