November 1st, 2011
03:00 PM ET
Even moderate drinking increases a woman’s breast cancer risk, according to a study published Tuesday in the Journal of the American Medical Association.
The research found as few as three to six glasses of wine a week increased the chance of developing breast cancer. The risk of breast cancer rose with the amount of alcohol consumed, the study found, with the best measure of risk being a woman’s cumulative alcohol consumption throughout her lifetime.
“This study doesn’t tell women, ‘Don’t drink at all,’” said Dr. Wendy Chen, lead author and assistant professor of medicine at Harvard Medical School. “It’s really what someone does on average over a long period of time, not what they did this past month, not what they did this past year.”
Previous studies have shown higher alcohol consumption associated with an increased risk of breast cancer. The effects of moderate drinking had not been calculated before.
In this study, funded by the National Institutes of Health, researchers found a 10% increase in risk with each 10 grams (3.5 ounces) per day of alcohol consumed. For example, women who consumed 3-6 glasses of wine per week had a breast cancer risk about 1.15 times higher than women who don’t drink.
There was no difference in cancer risk among wine, beer and liquor when the amount of alcohol in each was considered. Wine has 11 grams of alcohol per 4-ounce serving; beer, 12.8 grams per 12-ounce serving; liquor, 14 grams per standard serving.
Women who drank less than the equivalent of three glasses of wine per week showed no increased risk for breast cancer, the study found.
Chen said the studied showed alcohol added to whatever risk a woman already had for breast cancer. For example, if a woman had a family history of breast cancer, higher alcohol consumption added to that risk, she said.
Because moderate drinking has been associated with a lower death rate for heart disease, Chen said women should weigh the risks and benefits of drinking based on their own health histories.
Chen and her colleagues found no difference in risk based on what point in life the alcohol was consumed.
“Our results highlight the importance of considering lifetime exposure when considering the effect of alcohol” on cancer risk, the study concluded.
Chen and her colleagues used data from The Nurses’ Health Study, which began following more than 120,000 nurses in 1976 and first began asking participants about alcohol consumption in 1980. The researchers compared drinking habits with the 7,690 cases of invasive breast cancer among the nurses being followed.
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