O Alcohol consumption and liver cancer risk: a meta-analysis

Alcohol is a confirmed risk factor of liver cancer. Yet, its dose-response function and synergistic effects with other risk factors remain unclear. We performed a meta-analysis on publications up to May 2014. A total of 112 publications were identified. The meta-relative risk (mRR) and the dose-response trend were calculated. Tests for heterogeneity, publication bias, and sensitivity analyses were performed. The synergy index (SI) was recorded or calculated, whenever possible. Compared to individuals who never drank or drank at very low frequencies, the mRR for ever drinkers was 1.29 (95 % confidence interval, CI 1.16-1.42) and 1.46 (95 % CI 1.27-1.65) for case-control studies, and 1.07 (95 % CI 0.87-1.27) for cohort studies. Being a current drinker was associated with an increased liver cancer risk in case-control studies (mRR = 1.55, 95 % CI 0.38-2.73), but not in cohort studies (mRR = 0.86, 95 % CI 0.74-0.97). The dose-response relation between alcohol and liver cancer was apparent with RR = 1.08 (95 % CI 1.04-1.11) for 12 g/day (similar to 1 drink), 1.54 (95 % CI 1.36-1.74) for 50 g/day, 2.14 (95 % CI 1.74-2.62) for 75 g/day, 3.21 (95 % CI 2.34-4.40) for 100 g/day, and 5.20 (95 % CI 3.25-8.29) for 125 g/day of alcohol consumption. There were synergistic effects of alcohol consumption with hepatitis (S = 2.14, 95 % CI 1.31-2.98) and with diabetes (S = 3.57, 95 % CI 2.29-4.84) on the risk of liver cancer, although this may be subject to publication bias. Overall, one alcoholic drink per day (similar to 12 g/day) may be associated with a 1.1 times higher liver cancer risk. Further studies on the synergistic effects of alcohol consumption and other major risk factors are warranted.