Women who drink 30 grams of alcohol or more daily have a 43-percent greater risk of developing breast cancer than nondrinkers, according to researchers affiliated with the Women’s Health Study.
Harvard researcher
Shumin Zhang and colleagues studied data on about 39,000 women and also concluded that breast-cancer risk rises 11 percent for every 10-gram increase in daily alcohol consumption. The increased risk applied to estrogen- and progesterone-positive breast cancers.
Reference: Zhang, S.M., et al. (2007) Alcohol Consumption and Breast Cancer Risk in the Women’s Health Study. American Journal of Epidemiology, 165(6): 667-676.
Alcohol Self-Help News 
Very interesting information. I personally drink about once every six months in just a small amount. Hopefully I’m on the safer side of things. This makes me just want to quit all together though.