MicroRNAs used as novel biomarkers for detecting cancer metastasis

The low survival rates of cancers are primarily due to late diagnosis and metastasis. Discriminating the metastasis is a crucial factor for prognosis and improving the survival rate of cancer patients. MicroRNAs (miRNAs) can regulate the expression of hundreds of downstream genes, which has a broad effect on the regulation of the whole cell cycle. Accumulating studies have found that the aberrant expression of miRNAs is associated with cancer genesis. The aim of this study is to evaluate the diagnostic value of miRNAs in detecting cancer metastasis. Medline, PubMed, Embase, and CNKI were searched for relevant articles. Sensitivity, specificity, positive and negative likelihood ratio (PLR, NLR) and diagnostic odds ratio (DOR), the summary receiver operator characteristic (SROC) curve and the calculated AUC (area under the SROC curve) were applied to explore the diagnostic accuracy of miRNAs in metastasis. Seven hundred seventy-one metastatic cancer patients and 552 non-metastatic cancer controls from 14 articles were involved in our meta-analysis. A sensitivity of 0.75 (95% confidence interval (CI), 0.72-0.79) and a specificity of 0.80 (95% CI, 0.76-0.84) were observed from metastatic patients and non-metastatic controls in the combined analysis. And the AUC was 0.83 (95% CI, 0.79-0.86). In addition, results from subgroup analyses suggested that a higher diagnostic value for metastasis was acquired in tissue sample other than blood sample (sensitivity, 0.82 versus 0.73; specificity, 0.84 versus 0.79; PLR, 5.0 versus 3.5; NLR, 0.22 versus 0.34; DOR, 23 versus 10; AUC, 0.88 versus 0.80). In summary, this meta-analysis proved the relatively high diagnostic value of miRNA in metastasis, which might be applied as a novel screening tool to detect metastasis along with other biomarkers. We also illustrated that tissue-based miRNAs may have a better diagnostic accuracy than blood-based miRNAs.