Introduction : Although microvascular invasion (McVI) has prognostic value for patients with hepatocellular carcinoma (HCC) who have undergone hepatic resection, few studies have investigated the relationship between McVI and the aberrant expression of microRNAs. This study identified microRNAs selectively expressed in HCC with McVI and investigated their prognostic roles.

Methods : Clinical data and microRNA expression profiles for 355 HCC patients were extracted from The Cancer Genome Atlas database. MicroRNAs that were differentially expressed in the patients with McVI and those without vascular invasion were identified and investigated as potential prognostic factors for HCC.

Results : MicroRNA-9-5p was upregulated more (fold change [FC] 2.30; false discovery rate [FDR] < 0.001) and microRNA-675-5p was downregulated more (FC 0.52; FDR = 0.005) in the patients with McVI. Multivariate analysis revealed that the types of surgery (HR 1.718, 95% CI 1.169–2.524, P = 0.006), the presence of a residual tumor (HR 3.475, 95% CI 1.507–8.013, P = 0.003) and advanced TNM stage (HR 1.817, 95% CI 1.163–2.839, P = 0.009) were independently associated with tumor recurrence, and that advanced TNM stage and overexpression of microRNA-9 were independent risk factors for overall survival after hepatic resection for HCC (HR 1.671, 95% CI 1.114–2.508, P = 0.013 and HR 3.451, 95% CI 1.796–6.630, P < 0.001, respectively).

Conclusions : Overexpression of microRNA-9-5p was associated with McVI and poor survival of patients after hepatic resection for HCC.