Vitamin Analogues in Chemoprevention of Hepatocellular Carcinoma After Resection or Ablation—A Systematic Review and Meta-analysis

ObjectiveWhile hepatic resection or local ablative therapy may provide a potentially curative treatment for hepatocellular carcinoma (HCC), more than half of these patients develop recurrent HCC within 5 years after treatment. Thus identification of any therapy which can decrease or delay the incidence of recurrence will improve the results of treatment. However, no chemopreventive agent has been approved for HCC.MethodsA MEDLINE database, Embase, Cancerlit (National Cancer Institute), and CBM (Chinese Biomedical Database) search from 1990 to 2009 was performed to identify relevant articles using the keywords “hepatocellular carcinoma,” “vitamin analogue,” and “chemoprevention.” Additional papers were identified by a manual search of the references from the key articles. The fixed effect model was used for a meta-analysis.ResultsOral administration of acyclic retinoids (vitamin A analogue), and menatetrenone (vitamin K2 analogue) have been tested as chemopreventive agents after hepatic resection or local ablative therapy for HCC. There were one and four randomised, controlled trials (RCTs) which evaluated the efficacy of polyprenoic acid and menatetrenone, respectively. All studies were conducted in Japan. One RCT showed the preventive effect of polyprenoic acid in lowering the incidence of HCC recurrence after hepatic resection or percutaneous ethanol injection, and this effect lasted up to 199 weeks after randomization (or 151 weeks after completion of retinoid administration). Four RCTs evaluated the preventive efficacy of menatetrenone on HCC recurrence after hepatic resection or local ablative therapy. The results of three studies, as well as the meta-analysis of all four studies, showed significantly better tumour recurrencefree survival. The beneficial effect on the overall survival was less definite.ConclusionThere is evidence to suggest that chemopreventive therapy after partial hepatectomy or local ablative therapy is beneficial in prolonging disease-free survival, but the evidence is less for an effect on the overall survival. To confirm the beneficial role of vitamin A or K analogues in the chemoprevention of HCC further and larger randomised trials are now required.