Breast cancer and alcohol consumption: a case-control study in northern Italy.

From 1983 to 1986, a population-based case-control study of alcohol and breast cancer (250 cases and 499 controls) was conducted in a grape-farming area of northern Italy, where wine consumption is widespread. In the study population, 30% of women were abstainers and 15% reported alcohol intakes of 30 g/day or more. After adjustment for potential confounders, no appreciable association was evident for alcohol consumptions as high as 40 g/day. Women reporting intakes of more than 40 g/day showed approximately a 2-fold increase in the risk of breast cancer (relative risk, 1.9; 95% confidence interval, 1.1-3.3). A 2-fold increase in risk was observed for consumptions of more than 40 g/day of alcohol from wine, the most common alcoholic beverage in this population. These findings suggest that an association between alcohol intake and breast cancer may exist. However, the moderate risk observed seems to be limited to the relatively small group of women consuming daily amounts of alcohol in excess of 40 g, the equivalent of about half a bottle of wine or more.