Alcohol drinking and primary liver cancer: a pooled analysis of four Japanese cohort studies.

Because studies of the association between alcohol intake and the risk of primary liver cancer use varying cut-off points to classify alcohol intake, it is difficult to precisely quantify this association by meta-analysis of published data. Furthermore, there are limited data for women in prospective studies of the dose-specific relation of alcohol intake and the risk of primary liver cancer. We analyzed original data from 4 population-based prospective cohort studies encompassing 174,719 participants (89,863 men and 84,856 women). After adjustment for a common set of variables, we used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of primary liver cancer incidence according to alcohol intake. We conducted a meta-analysis of the HRs derived from each study. During 1,964,136 person-years of follow-up, 804 primary liver cancer cases (605 men and 199 women) were identified. In male drinkers, the multivariate-adjusted HRs (95% CI) for alcohol intakes of 0.1-22.9, 23.0-45.9, 46.0-68.9, 69.0-91.9 and ≥92.0 g/day, as compared to occasional drinkers, were 0.88 (0.57-1.36), 1.06 (0.70-1.62), 1.07 (0.69-1.66), 1.76 (1.08-2.87) and 1.66 (0.98-2.82), respectively (p for trend = 0.015). In women, we observed a significantly increased risk among those who drank ≥23.0 g/day, as compared to occasional drinkers (HR: 3.60; 95% CI: 1.22-10.66). This pooled analysis of data from large prospective studies in Japan indicates that avoidance of (1) heavy alcohol drinking (≥69.0 g alcohol/day) in men and (2) moderate drinking (≥23.0 g alcohol/day) in women may reduce the risk of primary liver cancer.