Drinking 3 or More Drinks per Week Raises Risk of Breast Cancer

Corroborating prior studies, a recent study on 106,000 women, found women who drank the equivalent of 3-6 glasses (4 oz. each) of wine per week were 15% more likely to develop breast cancer than women who never or rarely drank. Women who consumed much more alcohol -- about two glasses of wine or the equivalent of beer (12 oz.) or liquor (1.5 oz.) a day -- had a 51% increased chance of being diagnosed with breast cancer during nearly three decades of follow-up.  This study also found that even as few as three alcoholic drinks (a drink is defined as 4 oz. wine/12 oz. beer/1.5 oz. spirits) a month were associated with a slightly increased risk of breast cancer.  The risk was similar whether women drank wine, liquor or beer.

Prior research has also found an association between alcohol consumption and breast cancer. One reason for the connection may be that alcohol raises levels of circulating estrogen, and high levels of estrogen are linked to breast cancer.  What made this study unusual is that information was provided about women's alcohol consumption over several decades. Many other studies have asked about alcohol consumption at a single point in time, but drinking patterns may change over a lifetime. 

Another recent study looking at the relationship between drinking and breast cancer found that drinking alcohol may be especially risky for young women who have a family history of breast cancer (including having a mother, grandmothers or aunts with the disease).  In this study, researchers examined data on more than 9,000 girls from 1996 (when they were aged 9 to 15) through 2007.  They focused on 67 participants who were later diagnosed between the ages of 18 and 27 with benign breast disease, a large class of conditions that can cause breast lumps or pain and can be a risk factor for breast cancer.

The researchers found that women who have a family history of breast cancer or breast disease were about twice as likely to develop both benign breast disease and breast cancer than women with no family history of the disease.  Risk of benign breast disease rose along with how much alcohol the young women consumed.

What to do:  Breast cancer risk appears to increase with cumulative alcohol consumption.  Therefore, women who occasionally over-imbibe on vacation or at a holiday party shouldn't be alarmed.  And women who drink 1-2 drinks per week are likely not substantially raising their risk for breast cancer.  However for those who are drinking 6-10 or more drinks per week, risk of breast cancer is significantly increased.  Persons with a family history of breast cancer should be especially aware of their alcohol intake.  For all women, it is likely best to limit intake to no more than 3-4 drinks total per week.  Remember a drink is defined as 4 oz. of wine, 12 oz. of beer, or 1.5 oz. of spirits.  Many portions are larger than this and could count as 2 drinks even if they are served in one glass.  It is also true that previous studies have suggested a glass of red wine daily has significant cardiovascular benefits, so this has to be weighed against the breast cancer risk.  For cardiovascular benefits, among types of alcohol, red wine appears to be most beneficial.  Still, it is not recommended that women who do not drink should start consuming wine daily for its cardiovascular benefits.

SOURCES: Wendy Y. Chen, M.D., M.P.H., assistant professor, medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Mass; Steven A. Narod, M.D., professor, Dalla Lana School of Public Health, University of Toronto, and research chair, breast cancer, Women's College Research Institute, Toronto, Canada; Nov. 2, 2011, Journal of the American Medical Association.

Anees Chagpar, M.D., M.P.H., director, The Breast Center at Smilow Cancer Hospital at Yale-New Haven, and associate professor, department of surgery, Yale School of Medicine, New Haven, Conn.; Nov. 14, 2011, Washington University School of Medicine news release.

Adapted from articles at:  http://www.nlm.nih.gov/medlineplus/news/fullstory_118685.html and http://www.nlm.nih.gov/medlineplus/news/fullstory_118204.html