Moderate alcohol consumption’s links to breast cancer are real, but they might have been overestimated and could overshadow potential cardiovascular health benefits, caution authors of a new review. But others in the field urge clinicians to warn breast cancer survivors – and women at increased risk of developing breast cancer – not to drink regularly, even in moderation. 

Researchers agree that heavy drinking and binge drinking are deadly habits. But the suspected cardiovascular health benefits of regular, moderate alcohol consumption, and the resulting notion among the public that moderate drinking is “good for you,” are now so widely known that some wine labels sport pink breast cancer-awareness ribbons – much to the dismay of those concerned by epidemiological research linking even moderate alcohol consumption with elevated risks of breast cancer and other malignancies.

But those concerns about alcohol and cancer might be overblown, and more needs to be known about the molecular mechanisms of alcohol’s breast carcinogenicity before meaningful cost/benefit analyses of moderate drinking’s health effects can be done, argue Philip J. Brooks, PhD, and Samir Zakhari, PhD, both of the Division of Metabolism and Health Effects at the NIH’s National Institute on Alcohol Abuse and Alcoholism (NIAAA) in Bethesda, MD, in a paper published earlier this month in Alcohol: Clinical and Experimental Research. (The NIAAA has funded much of the research on moderate drinking’s cardiovascular health effects.)

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Their review of moderate alcohol consumption and breast cancer research literature supports the hypothesis that alcohol is indeed a breast carcinogen – albeit a “weak cumulative” one — and “may be a tumor promoter,” they acknowledge.

But factors such as the under-reporting of drinking habits by study participants might have yielded exaggerated estimates of the risk, they argue. 

“In addition to underreporting actual alcohol consumption in epidemiologic studies, another limitation is the lack of information about drinking pattern,” they wrote.

For example, Drs. Brooks and Zakhari point out, some studies ask women to report their drinking on a per-week basis and then divide by 7 to yield an estimated daily intake. That puts binge drinkers who drink 7 drinks on a Saturday night in the same category as moderate drinkers who have a glass of wine with dinner each night of the week.

“Clearly, drinking multiple drinks in the same sitting will result in higher blood alcohol levels than from a single drink, which can result in qualitatively different metabolic consequences, such as the induction of cytochrome P450 2E1 (CYP2E1) and the formation of free radicals,” they noted.