METHODS: Numerous electronic databases (MEDLINE, Embase, Pubmed, Google Scholar, and China Biology Medicine disc) were applied to retrieve relevant studies. Overall survival (OS) and progression-free survival (PFS) were used as primary endpoints. All statistical analyses were performed by RevMan software version 5.3.5 and STATA software version 14.1. In addition, the results of this meta-analysis were validated by an independent dataset from the Cancer Genome Atlas (TCGA).
RESULTS: A total of 11 studies containing 1124 patients were included in this meta-analysis. The pooled results showed that low miR-122 expression in HCC tissues significantly associated with unfavorable OS (hazard ratio [HR] = 1.48, 95% confidence interval [CI] 1.22-1.80, P < .001) and PFS (HR = 1.54, 95% CI 1.28-1.85, P < .001) in patients with HCC. However, the expression level of miR-122 in blood did not have the ability in predicting OS (HR = 0.75, 95% CI 0.44-1.28, P = .29) and PFS (HR = 0.84, 95% CI 0.58-1.20, P = .33) of HCC. Subgroup analysis further indicated that low expression of miR-122 in tumor tissues predicted poor OS in HCC patients who received curative liver resection (HR = 2.00, 95% CI 1.08-3.70, P = .03). Analysis using TCGA dataset suggested that low miR-122 expression in HCC tissues was significantly associated with OS (HR = 1.61, 95% CI 1.13-2.27, P = .008) other than PFS (HR = 1.30, 95% CI 0.96-1.75, P = .09).
CONCLUSIONS: Low miR-122 expression in HCC tissues was a reliable indicator for predicting the OS of HCC patients who underwent curative resection. Owing to the disagreement between this meta-analysis and the TCGA dataset, the predictive value of miR-122 in tissues for PFS needs to be verified by future well-designed studies with large sample size.