Alcohol intake and risk of stomach cancer: a pooled analysis of 20 cohorts

BACKGROUND: Stomach cancer presents complex etiologic heterogeneity. Ethanol in alcoholic beverages and its metabolite acetaldehyde are carcinogens causally linked to several cancers, but their role in gastric carcinogenesis has not been established. We analyzed harmonized, individual-level prospective data to examine associations between alcohol intake and risk of stomach cancer and its subtypes. METHODS: 2,009,951 participants in 20 cohorts (mean follow-up=9-29 years) within the Pooling Project of Prospective Studies of Diet and Cancer (n = 8,357 incident invasive gastric adenocarcinomas) were included. We used Cox regression to assess associations between alcohol intake and risk of stomach cancer overall and by anatomical and histological subtype and population subgroup, adjusting for confounders. RESULTS: Evidence for an association between alcohol intake and overall stomach cancer risk was weak (hazard ratio, HR, for ≥30 v 0.1-<5 g/day: 1.06 [95% confidence interval, CI, 0.96 to 1.16], P between-studies heterogeneity=0.43). Positive associations with stomach cancer risk were observed in never smokers (HR, for ≥30 v 0.1-<5 g/day: 1.20 [95% CI, 1.02 to 1.42]; P interaction=0.02) and for Asian studies (HR, 1.21 [95% CI, 1.02 to 1.42]; P interaction=0.01). Modest increased risks were observed for non-cardia cancers such as those of the fundus, body and greater curvature, but not distally located non-cardia cancers. HRs did not differ materially between diffuse- and intestinal-type cancers (P heterogeneity>0.05). CONCLUSION: There was little evidence of an overall association between alcohol intake and stomach cancer risk, although modest positive associations were observed among never smokers and in Asian cohorts.