Prognostic and diagnostic value of circRNA expression in colorectal carcinoma: a meta-analysis

Circular RNAs (circRNAs) are research hotspots in the network of noncoding RNAs in numerous tumours. The purpose of our study was to evaluate the clinicopathological, prognostic and diagnostic value of circRNAs in colorectal cancer. The PubMed, Cochrane Library, and Web of Science online databases were searched for relevant studies before May 15, 2019. Pooled hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated to assess the association between circRNAs expression, and overall survival (OS) and clinical parameters. Pooled sensitivity, specificity, and the area under the curve (AUC) were employed to assess the diagnostic value of circRNAs. A total of 19 studies were enrolled in this meta-analysis, with 11 on clinicopathological parameters, 8 on prognosis and 7 on diagnosis. For clinicopathological and prognostic value, elevated expression of oncogenic circRNAs was correlated with poor clinical parameters (tumor size: OR = 1.769, 95% CI: 1.097-2.852; differentiation grade: OR = 1.743, 95% CI: 1.032-2.946; TNM stage: OR = 3.320, 95% CI: 1.529-7.207; T classification: OR = 3.410, 95% CI: 2.088-5.567; lymph node metastasis: OR = 3.357, 95% CI: 2.160-5.215; distal metastasis: OR = 4.338, 95% CI: 2.503-7.520) and worse prognosis (HR = 2.29, 95% CI: 1.50-3.52). However, elevated expression of tumor-suppressor circRNAs was correlated with better clinical parameters (differentiation grade: OR = 0.453, 95% CI: 0.261-0.787; T classification: OR = 0.553, 95% CI: 0.328-0.934; distal metastasis: OR = 0.196, 95% CI: 0.077-0.498) and favorable prognosis (HR = 0.37, 95% CI: 0.22-0.64). For diagnostic value, the pooled sensitivity, specificity, and AUC were 0.82 (95% CI, 0.75-0.88), 0.72 (95% CI, 0.66-0.78), and 0.82 (95% CI, 0.78-0.85), respectively. These results indicate that circRNAs may be potential biomarkers for the diagnosis and prognosis of colorectal cancer.