Aims: Colorectal cancer (CRC) occupies an important position in the morbidity and mortality constitution of malignancies. In recent years, mounting literature has reported about the upregulating expression of microRNA-21 in blood and stool of CRC patients, which suggested that microRNA-21 may become a novel potential biomarker for CRC. Consequently, this meta-analysis was designed to systematically review the values of microRNA-21 in CRC diagnosis.
Methodology: Databases, including Cochrane library, PubMed, EMbase, Google Scholar, and Chinese National Knowledge Infrastructure, were scanned to retrieve relevant articles focusing on microRNA-21 in CRC diagnosis. Articles were then filtered according to the PRISMA statement and assessed by quality assessment of diagnosis accuracy studies-2. Sensitivity (SEN), specificity (SPE), positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio (DOR) were pooled using fixed-effects model or random-effects model. Summary receiver operating characteristic (SROC) curve and area under the curve (AUC) were used to estimate the overall diagnostic performance.
Results: A total of 15 studies, comprising 1268 CRC patients and 910 healthy controls, were enrolled in this meta-analysis. For serum miR-21, the pooled DOR, SEN, and SPE were 13.97 (95% CI: 8.44–23.11), 0.73 (95% CI: 0.69–0.77), and 0.83 (95% CI: 0.76–0.89), respectively; for plasma miR-21, the pooled DOR, SEN, and SPE were 8.03 (95% CI: 3.30–19.52), 0.67 (95% CI: 0.60–0.73), and 0.76 (95% CI: 0.69–0.81), respectively; and for fecal miR-21, the pooled DOR, SEN, and SPE were 7.06 (95% CI: 2.17–22.95), 0.33 (95% CI: 0.28–0.37), and 0.91 (95% CI: 0.88–0.93), respectively. Moreover, the AUC values of serum, plasma, and fecal miR-21 in CRC diagnosis were 0.8701, 0.8295, and 0.6742, respectively.
Conclusion: Blood miR-21 demonstrates good diagnostic performance, and serum samples are better than plasma samples in CRC diagnosis. For fecal miR-21, the sensitivity is unsatisfactory, but the specificity is favorable in predicting CRC patients.