While heavy alcohol intake has been regularly found to increase the risk of upper aero-digestive tract (UADT) cancers (mouth, tongue, pharynx, larynx, etc.), results are less clear for gastric cancer. The present study is notable because it is based on a large number of subjects, uses appropriate analytic methods, and provides dose-dependent results according to type of beverage.
For total alcohol, the dose-response results in this meta-analysis show a curvilinear relation between alcohol intake and gastric cancer, with a minimal (4%) but significant increase per typical drink (12.5 g/alcohol). However, there were varying responses for different beverages. In beverage-specific analyses, for beer, a non-linear relation was found with a significant increase of 7%/drink (CI 1.01, 1.13); for liquor, there was a linear association, with RR=1.03 (CI 0.98, 109); and for wine, the RR was 0.99 (CI 0.93, 1.06).
While the authors show a figure of the dose-response curves for each beverage using a non-linear approach, they do not provide the specific values in a table or in the text; this makes it difficult to clearly determine threshold effects of beverages. The figures suggest that the risk associated with beer consumption shows a slight decrease for 1 to 2 drinks/day, then an increase; for spirits, no decrease with lighter intake is seen; for wine, the curve is continuously downward. The authors do state that “light, moderate, and wine drinking would not increase gastric cancer risk,” so it is presumed that significant increased risk was not noted for moderate drinking for any specific beverage when non-linear effects were evaluated. Thus, overall, it appears that this large meta-analysis shows no significant increases in risk for light to moderate consumption of an alcoholic beverage, but a slight increase in risk associated with greater intake of beer and spirits. For wine, no increase in the risk of gastric cancer was seen for any level of consumption.
In a number of sensitivity analyses, the authors found tendencies for a lower gastric cancer risk associated with alcohol for cohort versus case-control studies, for studies with larger numbers of subjects, for studies judged to be of higher quality, and for studies adjusting for confounding by SES & income; these types of studies would be expected to yield more precise estimates of effect. These results led the authors to state these sensitivity analyses “ . . . indicate that our results may be exaggerated to some degree, but it should be noted that the pooled risk estimates of high-quality studies yielded similar results to the original analysis.”
Overall, Forum members considered this to be a well-done analysis, and the data support an increase in gastric cancer risk for heavier drinking (of beer or spirits) but no significant effects for light or moderate drinking of any alcoholic beverage. Forum members considered that if the lack of increase in cancer risk from wine consumption seen in this analysis proves to be true, it might relate to the polyphenols in wine that block any adverse effects of alcohol on gastric cancer risk.
Reference: Wang P-L, Xiao F-T, Gong B-C, Liu F-N. Alcohol drinking and gastric cancer risk: a meta-analysis of observational studies. Oncotarget 2017;8:99013-99023.