Diagnostic value of circulating miR-21 for colorectal cancer: a meta-analysis

MicroRNA-21 (miR-21) is highly expressed in the plasma of colorectal cancer (CRC) patients. Thus, miR-21 may be a useful novel diagnostic biomarker for CRC. This meta-analysis aims to verify the diagnostic value of circulating miR-21 in CRC patients. A literature search was conducted for publications that evaluated the diagnostic value of miR-21 for CRC. The quality of each study was scored with the Quality Assessment of Diagnostic Accuracy Studies. The bivariate meta-analysis model was employed to summarize the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR). Receiver operating characteristic curves were used to check the overall test performance. Five publications with six studies involving 579 patients and 266 controls were included in this meta-analysis. The pooled sensitivity was 77.4% [95% confidence interval (CI): 67.2%-85.1%], specificity was 84.6% (95% CI: 79.7%-88.5%), PLR was 5.02 (95% CI: 3.73-6.75), NLR was 0.27 (95% CI: 0.18-0.40), and DOR was 18.77 (95% CI: 10.41-33.83). The area under the summary ROC curve was 0.86. In addition, the results became prominent in the CRC group when a study that explored the advanced adenoma was excluded. Circulating miR-21 may be a suitable diagnostic biomarker for CRC with moderate sensitivity and specificity. Further studies should evaluate the diagnostic value of miR-21 for CRC in the future.