Microvascular invasion predicts a poor prognosis of solitary hepatocellular carcinoma up to 2 cm based on propensity score matching analysis

AIM: Microvascular invasion (MVI) is not discussed for solitary hepatocellular carcinoma (HCC) up to 2 cm in the 8th Edition of the American Joint Committee on Cancer Staging Manual. The present study aimed to reappraise the influence of MVI on solitary HCC up to 2 cm in diameter. METHODS: Between January 2010 and December 2012, a retrospective cohort of 496 HCC patients from the Eastern Hepatobiliary Surgery Hospital was analyzed. Propensity score matching was carried out to balance the baseline characteristics. Survival analysis was carried out using the Kaplan-Meier method. Risk factors were evaluated using the Cox proportional hazards model. Multivariate logistic regression was used to identify the risk factors associated with MVI. RESULTS: All patients were classified into either an MVI-negative group (n = 332) or an MVI-positive group (n = 164). The MVI-positive group had poorer recurrence-free survival and overall survival before and after propensity score matching. The multivariate analysis showed that MVI; being male; increased total bilirubin levels, alanine transaminase levels and γ-glutamyl transpeptidase levels; decreased albumin levels; and HBV DNA load >103  IU/mL were risk factors for recurrence-free survival. MVI, older age, lower albumin levels, and cirrhosis were risk factors for overall survival. Age 20 ng/mL, and lack of or an incomplete capsule were significantly independent predictors for MVI. CONCLUSIONS: MVI had a negative impact on the prognosis of solitary HCC up to 2 cm after curative hepatectomy. The 8th edition of the American Joint Committee on Cancer staging system could be improved by subdividing solitary HCC up to 2 cm according to MVI.