Systematic Review: the Association Between Obesity and Hepatocellular Carcinoma - Epidemiological Evidence

Background: Evidence increasingly implicates obesity as an independent risk factor for different cancers. We examined such evidence for hepatocellular carcinoma.

Aim: To review the effect of increased levels of body mass index on hepatocellular carcinoma risk.

Methods: We reviewed systematically the literature examining the association between increased body mass index and hepatocellular carcinoma risk. For each identified study, relevant data were extracted and appraised.

Results: Ten cohort studies (>90 million person-years), one nested case-control study (244 cases) and two case-control studies (494 cases) were identified. Of the cohort studies, 75% of person-years related to North Americans, 15% to East Asians, and 10% to Europeans. Three cohort studies adjusted for alcohol consumption, only one cohort study adjusted for hepatitis infection status. Seven cohort studies found a positive association between obesity (body mass index > or =30 kg/m(2)) and hepatocellular carcinoma risk (relative risks ranging from 1.4 to 4.1); two reported no association; and one reported a significant inverse association for a population subgroup (relative risk = 0.7, 95% confidence interval: 0.5-0.9).

Conclusion: Although most studies did not adjust for confounders and most data relate to a single world region, the overall evidence is suggestive of an increased hepatocellular carcinoma risk in obese and overweight individuals.