Women worried about their risk of breast cancer should drink less and exercise more, global cancer experts recommended Tuesday.
The study firms up what doctors have been saying for years about alcohol: women who drink every day raise their risk of a variety of cancers, including breast cancer.
That doesn’t mean that the occasional glass of wine or beer will cause cancer, and light drinking can lower the risk of heart disease. But less is better.
“Our Cancer Prevention Recommendations — for preventing cancer in general — include maintaining a healthy weight, being physically active, eating a healthy diet and limiting alcohol consumption (if consumed at all),” the American Institute for Cancer Research and the World Cancer Research Fund said in a joint report issued Tuesday.
Breast cancer is the No. 2 cancer killer of U.S. women, after lung cancer. Every year, it's diagnosed in 200,000 women and a few men, and kills around 40,000.
The study, covering 12 million women from around the world, found strong evidence that vigorous exercise and breastfeeding babies lowers the risk of breast cancer for all women, before and after menopause.
It also found strong evidence that being obese and drinking alcohol raises the risk of breast cancer.
The risk starts rising with as little as one drink a day on average, and goes up as women drink more.
“We have known about the link between alcohol and breast cancer as several studies have shown the association,” said Dr. Susan Boolbol, chief of the breast surgey division at the Icahn School of Medicine at Mount Sinai.
“The issue with those studies is that we did not have an exact amount of alcohol that was known to increase your risk. This study clearly states that one drink per day will increase your risk. That is major news,” added Boolbol, who was not involved in the study.
“We should continue to exercise and strive for moderate to vigorous exercise depending on our baseline health, strive to maintain a healthy weight and decrease alcohol intake.”
The WCRF/AICR report also confirmed major risk factors for breast cancer: early puberty with menstruation starting before age 12, menopause after age 55, not having children before the age of 30, chest x-rays and hormone pills, including some oral contraceptives and hormone replacement therapy.
It found limited evidence that eating vegetables and especially foods containing carotenoids — such as carrots — and eating calcium-rich foods might lower the risk of breast cancer.
One puzzling finding: Women who were overweight under the age of 30 had a lower risk of breast cancer after menopause. But gaining more weight as an adult clearly raised the risk. Researchers were not sure why or what this might mean, but stressed that weight gain later in life is a clear risk factor.