Women who consume one alcoholic drink per day are at elevated risk for breast cancer, according to a report from the World Cancer Research Fund and American Institute for Cancer Research.
The report’s authors indicated they found strong evidence that daily consumption of a small glass of wine or beer — equivalent to about 10 grams of alcohol — increases premenopausal breast cancer risk by 5% and postmenopausal breast cancer risk by 9%.
The report — titled “Diet, Nutrition, Physical Activity and Breast Cancer” — is based on analyses of 119 studies worldwide that included data from 12 million women, 260,000 of whom had breast cancer.
The findings provide insights into several links between lifestyle and breast cancer risk.
The authors found strong evidence that vigorous physical activity — such as fast bicycling or running — reduces risk for both pre- and postmenopausal breast cancers. The most active premenopausal women demonstrated a 17% reduced risk and the most active postmenopausal women demonstrated a 10% reduced risk compared with the least active women in each group.
Results showed mothers who breastfeed also are at reduced risk for breast cancer. In addition, being overweight or obese increases risk for postmenopausal breast cancer, as does greater weight gain during adulthood.
The authors found limited evidence that consumption of nonstarchy vegetables reduces risk for ER–negative breast cancers, and that dairy, high-calcium diets and foods that contain carotenoids reduce risk for some breast cancers.
“It can be confusing with single studies when the findings get swept back and forth,” Anne McTiernan, MD, PhD, cancer prevention researcher at Fred Hutchinson Cancer Research Center and one of the report’s authors, said in a press release. “With this comprehensive and up-to-date report, the evidence is clear: Having a physically active lifestyle, maintaining a healthy weight throughout life and limiting alcohol ... are all steps women can take to lower their risk.”
An estimated 252,710 women in the United States will be diagnosed with breast cancer this year, according to SEER statistics.
Age, family history and other factors beyond a person’s control contribute to risk. However, the American Institute for Cancer Research estimated that one in three cases could be prevented if women were physically active, maintained a healthy weight and did not drink alcohol.
“Wherever you are with physical activity, try to nudge it up a bit, either a little longer or a little harder,” Alice Bender, MS, RDN, the institute’s head of nutrition programs, said in the release. “Make simple food shifts to boost protection — substitute veggies like carrots, bell peppers or green salad for chips and crackers, and if you drink alcohol, stick to a single drink or less. There are no guarantees when it comes to cancer, but it is empowering to know you can do something to lower your risk.”