Elevated miR-21 is associated with poor prognosis in non-small cell lung cancer: a systematic review and meta-analysis.

ABSTRACT

OBJECTIVE: Increasing studies have investigated the prognostic value of high miR-21 expression in non-small cell lung cancer (NSCLC) with inconsistent results. We conducted this meta-analysis to explore whether the expression of miR-21 was associated with prognosis in NSCLC patients. MATERIALS AND METHODS: We systematically searched Medline, EMBASE, Web of Science and Cochrane Library for relevant studies. Studies exploring the relationship between miR-21 expression and NSCLC prognosis and clinical pathology, and reporting enough data to get the hazard ratio (HR) and 95% confidence intervals (CIs), were included. Random- or fixed-effect models were employed to calculated pooled hazard ratios (HRs) or risk ratio and 95% confidence intervals (95% CIs). RESULTS: A total of 28 eligible studies, including 24 for prognosis, 16 for clinicopathological features were identified. Our results revealed that elevated miR-21 was related to unfavorable overall survival (OS) in NSCLC (HR = 1.960, 95% CI = 1.510-2.554, p = 0.000). Similar results were found in disease-free survival, relapse-free survival, and cancer-special death. In a meta-analysis of clinical pathology, overexpressed miR-21 was significantly related to lung adenocarcinoma, larger tumor size, and advanced clinical stage. CONCLUSIONS: Our meta-analysis suggested that miR-21 may function as an unfavorable biomarker of prognosis in NSCLC patients.