Population attributable risk of aflatoxin-related liver cancer: systematic review and meta-analysis.

BACKGROUND Over 4 billion people worldwide are exposed to dietary aflatoxins, which cause liver cancer (hepatocellular carcinoma, HCC) in humans. However, the population attributable risk (PAR) of aflatoxin-related HCC remains unclear. METHODS In our systematic review and meta-analysis of epidemiological studies, summary odds ratios (ORs) of aflatoxin-related HCC with 95% confidence intervals were calculated in HBV+ and HBV- individuals, as well as the general population. We calculated the PAR of aflatoxin-related HCC for each study as well as the combined studies, accounting for HBV status. RESULTS Seventeen studies with 1680 HCC cases and 3052 controls were identified from 479 articles. All eligible studies were conducted in China, Taiwan, or sub-Saharan Africa. The PAR of aflatoxin-related HCC was estimated at 17% (14-19%) overall, and higher in HBV+ (21%) than HBV- (8.8%) populations. If the one study that contributed most to heterogeneity in the analysis is excluded, the summarised OR of HCC with 95% CI is 73.0 (36.0-148.3) from the combined effects of aflatoxin and HBV, 11.3 (6.75-18.9) from HBV only and 6.37 (3.74-10.86) from aflatoxin only. The PAR of aflatoxin-related HCC increases to 23% (21-24%). The PAR has decreased over time in certain Taiwanese and Chinese populations. CONCLUSIONS In high exposure areas, aflatoxin multiplicatively interacts with HBV to induce HCC; reducing aflatoxin exposure to non-detectable levels could reduce HCC cases in high-risk areas by about 23%. The decreasing PAR of aflatoxin-related HCC reflects the benefits of public health interventions to reduce aflatoxin and HBV.