MicroRNAs as Biomarkers for the Diagnostics of Bladder Cancer: a Meta-Analysis

Background: Bladder cancer (BCa) is the fifth most common cancer with significant morbidity and mortality. Recently, numerous studies demonstrated that microRNAs (miRNAs) are emerging as diagnostic biomarkers for BCa. However, the findings in these studies are inconsistent. To systematically assess the potential diagnostic value of miRNAs for BCa, a meta-analysis was performed in this study. Methods: Relevant literature was researched in PubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), and WanFang databases up to September 1, 2014. The pooled sensitivity, specificity, positive likelihood ratio (PLR), negative LR (NLR), diagnostic odds ratio (DOR), and area under the SROC curve (AUC) value were analyzed by the random-effects model, whose parameters reflected the overall diagnostic performance of miRNAs. Results: Thirty studies from 10 individual publications, including 1019 BCa patients and 690 controls, were included in this meta-analysis. The pooled sensitivity, specificity, PLR, NLR, DOR, and AUC were 0.80 (95% CI: 0.78 - 0.81), 0.74 (95% CI: 0.72 - 0.76), 3.22 (95% CI: 2.68 - 3.87), 0.26 (95% CI: 0.21 - 0.32), 15.20 (95% CI: 10.25 - 22.53) and 0.85, respectively, indicating a moderate diagnostic accuracy for BCa. Moreover, our subgroup analyses showed that analysis of multiple miRNAs (AUC, sensitivity, and specificity of 0.913, 0.86, and 0.80, respectively) yielded a higher diagnostic accuracy than of single miRNAs (AUC, sensitivity, and specificity of 0.84, 0.78, and 0.73, respectively) in BCa diagnosis. In addition, as biomarkers, miRNAs are more suitable for the diagnosis of non-muscle-invasive BCa (NMIBCa) with AUC of 0.84, sensitivity of 0.74, and specificity of 0.77 than muscle-invasive BCa (MIBCa) with AUC of 0.79, sensitivity of 0.73, and specificity of 0.73. Conclusions: The present meta-analysis suggests that miRNAs are potential novel biomarkers for detection of BCa. However, further validation studies are still needed to confirm our findings.