"Overall, we found that alcohol use accounted for approximately 3.5% of all cancer deaths, or about 19 500 persons, in 2009. It was a prominent cause of premature loss of life, with each alcohol-attributable cancer death resulting in about 18 years of potential life lost. Although cancer risks were greater and alcohol-attributable cancer deaths more common among persons who consumed an average of more than 40 grams of alcohol per day (‡ 3 drinks), approximately 30% of alcohol-attributable cancer deaths occurred among persons who consumed 20 grams or less of alcohol per day. About 15% of breast cancer deaths among women in the United States were attributable to alcohol consumption."
David E. Nelson, Dwayne W. Jarman, Jürgen Rehm, Thomas K. Greenfield, Grégoire Rey, William C. Kerr, Paige Miller, Kevin D. Shield, Yu Ye, and Timothy S. Naimi. (2013). Alcohol-Attributable Cancer Deaths and Years of Potential Life Lost in the United States. American Journal of Public Health. e-View Ahead of Print.