Alcohol and liver cancer: a systematic review and meta-analysis of prospective studies

Despite several studies support a positive association between heavy alcohol consumption and liver cancer risk, a consistent dose-risk relationship has not yet been established. We carried out a systematic review and a meta-analysis of the association between alcohol intake and liver cancer occurrence, following the Meta-analysis Of Observational Studies in Epidemiology guidelines. We searched for cohort and nested case-control studies on the general population published before April 2013, using PubMed and EMBASE. Summary meta-analytic relative risks (RRs) were estimated using random-effect models. We included 16 articles (19 cohorts) for a total of 4445 incident cases and 5550 deaths from liver cancer. Compared with non-drinking, the pooled RRs were 0.91 (95% confidence interval, CI, 0.81-1.02) for moderate drinking (< 3 drinks per day) and 1.16 (95% CI, 1.01-1.34) for heavy drinking (≥ 3 drinks per day), with significant heterogeneity among studies. The dose-risk curve suggested a linear relationship with increasing alcohol intake in drinkers, with estimated excess risk of 46% for 50 g of ethanol per day and 66% for 100 g per day. This systematic review suggests a moderate detrimental role of consumption of 3 or more alcoholic drinks per day on liver cancer, and a lack of association with moderate drinking. Our results have to be taken with due caution on account of the possible limitations of the original studies included in the meta-analysis.