Background & aims: Nonalcoholic fatty liver disease (NAFLD) has been implicated as a cause of hepatocellular carcinoma (HCC). We performed a systematic review of epidemiology studies to confirm the association between these disorders.

Methods: We searched PubMed for original reports published from January 1992 to December 2011 that evaluated the association between NAFLD, nonalcoholic steatohepatitis (NASH), cryptogenic cirrhosis presumed to be NASH-related, and the risk of HCC. Studies were categorized as offering potential direct evidence (eg, cohort studies) or indirect evidence (eg, case-control, cross-sectional, or case-series studies) for an association. We analyzed data from a total of 17 cohort studies (3 population based, 9 clinic based [6 limited to patients with cirrhosis], and 5 natural history), 18 case-control and cross-sectional studies, and 26 case series.

Results: NAFLD or NASH cohorts with few or no cases of cirrhosis cases had a minimal risk for HCC (cumulative HCC mortality of 0%-3% for study periods up to 20 y). Cohorts with NASH and cirrhosis had a consistently higher risk (cumulative incidence ranging from 2.4% over 7 y to 12.8% over 3 y). However, the risk for HCC was substantially lower in these cohorts than for cohorts with hepatitis C-related cirrhosis. Factors that increased risk among cohorts with NASH and cirrhosis could not be determined, because most studies were not sufficiently powered for multivariate analysis.

Conclusions: This systematic review shows that despite several limitations, there is epidemiologic evidence to support an association between NAFLD or NASH and an increased risk of HCC; risk seems to be limited to individuals with cirrhosis.