Prognostic significance of microRNA-135 in patients with digestive system cancers: a systematic review and meta-analysis

Background: MicroRNA-135 (miR-135) is a well-known non-coding RNA that has been demonstrated to participate in tumorigenesis and cancer development; however, the clinical prognostic value of miR-135 in digestive system cancers remains controversial. This meta-analysis aims to explore the potential value of miR-135 as a prognostic marker for digestive system cancers. Methods: The PubMed, Embase, Cochrane Library, and Web of Science databases were searched for eligible articles published before 31 August 2019. Stata 12.0 software was used to analyze the overall survival (OS), disease-free survival (DFS), and recurrence-free survival (RFS) rates to access the prognostic value of miR-135 in digestive system cancers. We then used The Cancer Genome Atlas (TCGA) datasets to validate the meta-analysis results. Results A total of 1470 patients from 17 studies were included in this meta-analysis. The pooled results showed that enhanced miR-135 expression was significantly associated with poor OR (hazard ratio (HR): 1.790; 95% confidence interval (95% CI): 1.577–2.031; P=0.000), DFS (HR: 1.482; 95% CI: 0.914–2.403; P=0.110), and RFS (HR: 3.994; 95% CI: 1.363–11.697; P=0.012) in digestive system cancers. A sensitivity analysis confirmed the reliability of our findings, and no significant publication bias was observed. Conclusion: MiR-135 can be used as a novel biomarker for patients with digestive system cancers. We look forward to future large-scale clinical studies that will investigate the prognostic value of miR-135.