Objective: Published data have shown that microRNAs (miRNAs) could play a potential role as diagnosticand prognostic indicators in cancers. Data for the predictive value of microRNA-155 are inconclusive. The aimof the present analysis was therefore to evaluate the role of miR-155 in prognosis for patients with a variety ofcarcinomas.
Methods: Relevant studies were identified by searching PubMed and EMBASE. Data were extractedfrom studies comparing overall survival (OS), recurrence-free survival (RFS) or cancer-specific survival (CSS)in patients with carcinoma with higher miR-155 expression and those with lower levels. The pooled hazard ratios(HRs) and 95% confidence intervals (CIs) of miR-155 for clinical outcome were calculated.
Results: A total of 15studies were included. The pooled hazard ratio (HR) for OS of higher miR-155 expression in cancerous tissuewas 1.89 (95% CI: 1.20-2.99, P =0.006), which could markedly predict poorer survival in general cancer. ForRFS/CSS, elevated miR-155 was also associated with poor prognosis of cancer (HR= 1.50, 95% CI: 1.10-2.05, P= 0.01). On subgroup analysis, the pooled HR for OS in non-small cell lung cancer (NSCLC) was 2.09 (95% CI:0.68-6.41, P > 0.05), but for RFS/CSS was 1.28 (95% CI: 1.05-1.55, P = 0.015), with statistical significance; thepooled HRs for OS and RFS/CSS in digestive system neoplasms were 3.04 (95% CI: 1.48-6.24, P =0.003) and2.61 (95% CI: 1.98-3.42, P<0.05), respectively.
Conclusions: The results indicated that the miR-155 expressionlevel plays a prognostic role in patients with cancer, especially NSCLCs and digestive system carcinomas.