Harvard Women's Health Watch

Study suggests scant increased risk of breast cancer from alcohol intake

Research we're watching

A study published Oct. 15, 2015, in the International Journal of Cancer adds to evidence that the risk of breast cancer increases—but not very much—with every drink a woman takes. Researchers from five Spanish universities followed 334,850 women, ages 35 to 70, from 10 European countries. During an 11-year period, 11,576 were diagnosed with breast cancer.

When the researchers compared alcohol intake among women who developed breast cancer and those who didn't, they found women who averaged two drinks a day had a 4% higher risk than those who limited their consumption to one daily drink. Those who averaged three drinks a day had a 6% higher breast cancer risk.

In reality, the increase is relatively small. At age 35, the average woman's absolute risk of developing breast cancer in the next decade is around 1%. Increasing it by 4% or 6% wouldn't raise it much above 1%. At age 70, a woman's 10-year risk is 3.9%; a 6% increase would raise it to 4.1%.

Although alcohol may play a minor role in increasing breast cancer risk, there are stronger reasons for women to limit their consumption to a drink a day, including an increased risk of cardiovascular disease and Alzheimer's disease. As for reducing your breast cancer risk, other lifestyle interventions—such as following the Mediterranean diet and avoiding postmenopausal weight gain—will probably have a greater impact.