MicroRNAs in the prognosis of triple-negative breast cancer: A systematic review and meta-analysis

BACKGROUND: Triple-negative breast cancer (TNBC) is a heterogeneous group of tumors characterized by their aggressive nature and poor associated survival. MicroRNAs (miRs) have been found to play an important role in the occurrence and development of human cancers, but their role in the prognosis of TNBC patients remains unclear. We performed a meta-analysis to explore the prognostic value of miRs in TNBC. METHODS: We systematically searched the PubMed, Embase, and Web of Science databases to identify eligible studies. A meta-analysis was performed to estimate the pooled hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) for the associations between levels of miR expression (predictive factors) and overall survival (OS) and disease-free survival (DFS) (outcomes) in patients with TNBC. RESULTS: After performing the literature search and review, 21 relevant studies including 2510 subjects were identified. Six miRs (miR-155, miR-21, miR-27a/b, miR-374a/b, miR-210, and miR-454) were assessed in the meta-analysis. Decreased expression of miR-155 was associated with reduced OS (adjusted HR = 0.58, 95% CI: 0.34–0.99; crude HR = 0.67, 95% CI: 0.58–0.79). High miR-21 expression was also predictive of reduced OS (crude HR = 2.50, 95% CI: 1.56–4.01). We found that elevated levels of miR-27a/b, miR-210, and miR-454 expression were associated with shorter OS, while the levels of miR-454 and miR-374a/b expression were associated with DFS. CONCLUSIONS: Specific miRs could serve as potential prognostic biomarkers in TNBC. Due to the limited research available, the clinical application of these findings has yet to be verified.