Background & aims: Mounting evidence indicates that coffee drinking may protect against liver injury and lower the risk of liver cancer. We quantitatively assessed the relation between coffee consumption and the risk of liver cancer in a meta-analysis of epidemiologic studies.
Methods: Relevant studies were identified by searching MEDLINE (from 1966 to February 2007) and the reference lists of retrieved articles. We included cohort and case-control studies that reported relative risk (RR) estimates with 95% confidence intervals (CIs) of primary liver cancer or hepatocellular carcinoma by quantitative categories of coffee consumption. Study-specific RRs were pooled using a random-effects model.
Results: Four cohort and 5 case-control studies, involving 2260 cases and 239,146 noncases, met the inclusion criteria. All studies observed an inverse relation between coffee consumption and risk of liver cancer, and in 6 studies the association was statistically significant. Overall, an increase in consumption of 2 cups of coffee per day was associated with a 43% reduced risk of liver cancer (RR, 0.57; 95% CI, 0.49-0.67). There was no statistically significant heterogeneity among studies (P = .17). In stratified analysis, the summary RRs of liver cancer for an increase in consumption of 2 cups of coffee per day were 0.69 (95% CI, 0.55-0.87) for persons without a history of liver disease and 0.56 (95% CI, 0.35-0.91) for those with a history of liver disease.
Conclusions: Findings from this meta-analysis suggest that an increased consumption of coffee may reduce the risk of liver cancer.