Alcohol as a Breast Cancer Risk

Karen Collins, MS, RD, CDN

American Institute for Cancer Research

            While breast cancer risk is impacted by several lifestyle choices (specifically, weight control, physical activity and breastfeeding), research shows that it may be less affected by dietary choices than some other cancer sites. The major exception: alcohol consumption.

According to the latest report on diet and cancer risk published by the American Institute for Cancer Research (AICR), there is convincing evidence that alcohol intake raises risk for breast cancer. An analysis of the research compiled by AICR found that breast cancer risk increases 6 to 10 percent for every 3 ounces of wine, 9 ounces of beer or 1 ounce of 80-proof liquor consumed each day. Subsequent research supports these figures, noting a 3 to 15 percent increased risk for similar daily consumption.  

Alcohol may exert its impact in several different ways and researchers are working to identify who may be most at risk. Many of the potential hypotheses involve mechanisms that foster DNA damage and can trigger the process of cancer development.

For example, alcohol may disrupt absorption and use of folate, a B vitamin needed for production and repair of DNA.   (Although some experts suggest that women who meet daily folate recommendations are less at risk, this is not seen consistently.)    Another possibility is the breakdown of alcohol into acetaldehyde in the body, a compound that can react with cells’ DNA and has been shown to cause cancer in animals.   Lastly, when alcohol is metabolized, free radicals form; these highly reactive substances can cause DNA damage as well.

 In addition to its more general role in promoting DNA damage, alcohol affects breast cancer risk specifically by raising body levels of estrogen.   According to the research, estrogen-sensitive breast cancers are much more likely to be affected by alcohol than the less common estrogen-negative forms of the disease. Alcohol’s impact does not seem to differ based on pre- or post-menopausal status.

Genetics may also play a role in assessing the risk associated with alcohol consumption. People who inherit different forms of alcohol metabolizing enzymes may be affected by alcohol differently. However, researchers are a long way from being able to identify individual differences in safe levels of alcohol consumption.

So how much alcohol can a woman safely consume? According to many experts, risk is likely minimal with consumption of one standard drink per day   (equivalent to 5 ounces of wine, 12 ounces of beer and 1.5 ounces of 80-proof liquor). The important message: Risk clearly increases as the amount imbibed increases.

But be warned – some emerging research suggests that even small increases in daily alcohol consumption may have drastic consequences.   A new study recently presented at a major cancer research conference reported that, compared to women who did not drink any alcohol, risk of hormone-sensitive post-menopausal breast cancer increased 7 percent among those who consumed less than one drink daily. That figure jumped to a 32 percent increase with one to two drinks daily, and to a 51 percent increase with three or more drinks daily.

Women who face other risk factors, particularly those with a family or personal breast cancer history, might choose to limit alcohol consumption to less than one standard drink per day or abstain altogether. Also since weight control has such a large impact on risk of post-menopausal breast cancer, limiting the “empty calories” of alcohol may bring double benefits.

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The American Institute for Cancer Research (AICR) is the cancer charity that fosters research on the relationship of nutrition, physical activity and weight management to cancer risk, interprets the scientific literature and educates the public about the results. It has contributed more than $86 million for innovative research conducted at universities, hospitals and research centers across the country. AICR has published two landmark reports that interpret the accumulated research in the field and is committed to a process of continuous review. AICR also provides a wide range of educational programs to help millions of Americans learn to make dietary changes for lower cancer risk. Its award-winning New American Plate program is presented in brochures, seminars and on its Web site, www.aicr.org. AICR is a member of the World Cancer Research Fund International.