Introduction: Many studies have reported that microRNA-21 (miR-21) mihght predict the survival outcome in non-small cell lung cancers (NSCLCs) but the opposite opinion has also been expressed. The aim of this study was to summarize the evidence for a prognostic role of miR-21.
Materials and methods: All the eligible studies was searched by Medline and EMBASE and patients' clinical characteristics and survival outcome were extracted. Then a meta-analysis was performed to clarify the prognostic role of the miR-21 expression in different subgroups.
Results: A total of 8 eligible articles were yielded covering survival outcomes or clinical characteristics. The combined hazard ratio (HR) and 95% confidence interval (95% CI) for overall survival (OS) was 2.19 [0.76, 6.30], while the combined HR (95% CI) of Asian group for OS had a significant result, 5.49 [2.46, 12.27]. The combined HR (95% CI) for recurrence free survival or disease free survival (RFS/DFS) was 2.31 [1.52, 3.49]. Odds ratios (ORs) showed that the miR-21 expression was associated with lymph node status and histological type.
Conclusion: miR-21 expression could predict the prognostic outcome of NSCLC in Asians, despite some deficiencies in the study data.