Prediction of poor prognosis in breast cancer patients based on microRNA-21 expression: a meta-analysis

PLoS One. 2015 Feb 23;10(2):e0118647. doi: 10.1371/journal.pone.0118647. eCollection 2015.


Background: MicroRNA-21 (miRNA-21 or miR-21) may act as a prognostic biomarker of cancer. However, the available evidence is controversial. Therefore, the present meta-analysis summarizes this evidence and evaluates the prognostic role of this gene in breast cancer.

Methods: The meta-analysis was conducted by searching the databases of PubMed, EMBASE, Web of Science and Chinese database-China National Knowledge Infrastructure (CNKI). Data were extracted from studies that investigated the association between miR-21 expression and survival outcomes in breast cancer patients. With respect to survival outcomes, the pooled hazard ratios (HRs) of miR-21 were calculated given a 95% confidence interval (CI).

Results: Our meta-analysis identified a total of 10 studies involving 1,439 cases. Further investigation demonstrated that a high miR-21 expression can predict poor overall survival (OS) (HR = 2.57, 95% CI: 1.37-4.81, P = 0.003) and shortened disease-free/recurrence-free survival (DFS/RFS) (HR = 1.45, 95% CI: 1.16-1.82, P = 0.001) in breast cancer patients. Moreover, high miR-21 expression was significantly correlated with lowered OS in the Asian group (HR = 5.07, 95% CI: 2.89-8.92, P < 0.001), but not in the Caucasian cohort (HR = 1.44, 95% CI: 0.99-2.10, P = 0.058). Furthermore, odds ratios (ORs) showed that up-regulated miR-21 levels were associated with multiple clinical characteristics.

Conclusion: Our results indicated that miR-21 can predict unfavorable prognoses in breast cancer patients, especially in Asians.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Breast Neoplasms / genetics*
  • Breast Neoplasms / pathology
  • Female
  • Humans
  • MicroRNAs / genetics*
  • Prognosis


  • MIRN21 microRNA, human
  • MicroRNAs

Grant support

This work was supported by grants from SZZ’s National Natural Science Foundation of China (No. 91229104), The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.