Aflatoxin B₁ Exposure, Hepatitis B Virus Infection, and Hepatocellular Carcinoma in Taiwan

Abstract

To evaluate the role of aflatoxin B₁ (AFB₁) exposure on risk of hepatocellular carcinoma (HCC), a case-control study nested within a community-based cohort was conducted. Baseline blood and urine samples were used to determine the level of AFB₁-albumin adducts and urinary AFB₁ metabolites. Conditional logistic regression analysis was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI) to assess the effect of AFB₁ exposure on risk of HCC. The adjusted ORs (95% CIs) were 1.54 (1.01-2.36) and 1.76 (1.18-2.58), respectively, for those with AFB₁-albumin adducts and urinary AFB₁ metabolite levels above the mean compared with those with levels below the mean. When compared with subjects in the lowest quartile of urinary AFB₁ metabolites, there was an increase in risk of HCC, with adjusted ORs (95% CIs) of 0.57 (0.14-2.43), 1.43 (0.32-6.42), and 4.91 (1.18-20.48; P_trend = 0.02), respectively, among noncarriers of hepatitis B virus (HBV) infection. The adjusted OR (95% CI) was 7.49 (5.13-10.93) for carriers of hepatitis B surface antigen compared with noncarriers, regardless of AFB₁ status. The ORs (95% CI) were 10.38 (5.73-18.82) and 15.13 (7.83-29.25) for carriers of hepatitis B surface antigens with levels of AFB₁-albumin adducts and urinary AFB₁ metabolites above the mean, respectively. The combined effect of aflatoxin exposure and HBV infection did not differ by duration of follow-up. Consistent with our previous study with fewer subjects, these data show that AFB₁ exposure is a risk factor for HCC risk. However, in this larger study, the effect of combined AFB₁ exposure and HBV infection is more consistent with an additive than a multiplicative model. (Cancer Epidemiol Biomarkers Prev 2009;18(3):846–53)