Abstract
INTRODUCTION: Circular RNAs (circRNAs) play critical roles in tumorigenesis, but their clinical efficacy in esophageal squamous cell carcinoma (ESCC) still retains controversial. This meta-analysis aims at evaluating the associations between circRNA expressions and clinicopathologic features as well as the diagnostic and prognostic values of circRNAs in ESCC. MATERIALS & METHODS: PubMed, EMBASE, and other online databases were systematically searched to collect studies on circRNAs and clinicopathological features, diagnostic, and/or prognostic assessments of ESCC. The quality of included studies was evaluated using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) and Newcastle-Ottawa Scale (NOS) scales. The included studies were quantitatively weighted and merged, and diagnostic indicators, hazard ratios (HRs) and the corresponding 95% confidence intervals (CIs) were calculated. P values were merged by Fisher᾽s method. Sources of heterogeneity were traced using subgroup, sensitivity, and meta-regression analyses. RESULTS: As a result, 12 studies were included, representing 769 ESCC patients. The meta-analysis showed that abnormal expressions of circRNAs were associated to TNM stage as well as lymph node and distant metastases in ESCC cases. CircRNA was used to distinguish ESCC patients from healthy controls, and the merged sensitivity, specificity, and the area under the curve (AUC) of ESCC were 0.78 (95% CI: 0.74-0.81), 0.79 (95% CI: 0.75-0.83), and 0.86, respectively. The survival analysis showed that upregulated oncogenic circRNA levels in ESCC tissues was associated with the shorter overall survival (OS) of the patients (univariate analysis: HR = 2.25, 95% CI: 1.71-2.95, p = 0.000, I(2 ) = 0.0%; multivariate analysis: HR = 2.50, 95% CI: 1.61-3.89, p = 0.000, I(2) = 0.0%), while the OS of ESCC patients presenting overexpressions of tumor-suppressive circRNAs was significantly ameliorated (HR = 0.29, 95% CI: 0.20-0.42, p = 0.000, I(2) = 0.0%). The subgroup analyses based on circRNA biofunctions, sample size, and reference gene also revealed robust results. CONCLUSION: CircRNAs can be used as promising molecular biomarkers for the early diagnosis and prognosis monitoring of ESCC.