The impact of obesity and diabetes mellitus on the risk of hepatocellular carcinoma

Background: Obesity has been associated to increased hepatocellular carcinoma (HCC) risk, but studies on the topic do not fully account for hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. Likewise, an increased risk has been reported for diabetes mellitus (DM) but whether DM is an independent risk factor has not been established yet. To evaluate the association of obesity and DM with HCC risk, we conducted a hospital-based, case-control study in two Italian areas. Patients and methods: From 1999 to 2003, 185 HCC cases and 404 hospital controls were enrolled. Blood samples were obtained for HBV and HCV screening. Results: After allowance for known risk factors, body mass index >= 30 kg/m(2) [odds ratio (OR) = 1.9, 95% confidence interval (CI) 0.9-3.9] and DM (OR = 3.7, 95% CI 1.7-8.4) were associated to HCC risk. These associations persisted (OR = 3.5, 95% CI 1.6-7.7 for obesity; OR = 3.5, 95% CI 1.3-9.2 for DM) among subjects without HBV and/or HCV infection. Overall, 23% of HCC cases seemed attributable to these conditions, and this figure rose to 37% among subjects without HBV and/or HCV infections. Conclusions: The present study provides further evidence that obesity and DM increase HCC risk and that these factors may explain a relevant proportion of cases among subjects without markers of HBV/HCV infection.