Alcohol intake and stomach cancer risk in Japan: A pooled analysis of six cohort studies

The association between alcohol intake and stomach cancer risk remains controversial. We undertook a pooled analysis of data from six large-scale Japanese cohort studies with 256 478 participants on this topic. Alcohol intake as ethanol was estimated using a validated questionnaire. The participants were followed for incidence of stomach cancer. We calculated study-specific hazard ratios (HRs) and 95% confidence intervals (CIs) for stomach cancer according to alcohol intake using a Cox regression model. Summary HRs were estimated by pooling the study-specific HRs using a random-effects model. During 4 265 551 person-years of follow-up, 8586 stomach cancer cases were identified. In men, the multivariate-adjusted HRs (95% CIs) of stomach cancer were 1.00 (0.87-1.15) for occasional drinkers, and 1.00 (0.91-1.11) for <23 g/d, 1.09 (1.01-1.18) for 23 to <46 g/d, 1.18 (1.09-1.29) for 46 to <69 g/d, 1.21 (1.05-1.39) for 69 to <92 g/d, and 1.29 (1.11-1.51) for >= 92 g/d ethanol in regular drinkers compared with nondrinkers. In women, the multivariate-adjusted HRs were 0.93 (0.80-1.08) for occasional drinkers, and 0.85 (0.74-0.99) for <23 g/d, and 1.22 (0.98-1.53) for >= 23 g/d in regular drinkers compared with nondrinkers. The HRs for proximal and distal cancer in drinkers vs nondrinkers were 1.69 (1.15-2.47) and 1.24 (0.99-1.55) for >= 92 g/d in men, and 1.60 (0.76-3.37) and 1.18 (0.88-1.57) for >= 23 g/d in women, respectively. Alcohol intake increased stomach cancer risk in men, and heavy drinkers showed a greater point estimate of risk for proximal cancer than for distal cancer.