Moderate Drinking Raises Risk of Breast Cancer

Many studies of risk factors for breast cancer include alcohol consumption, but details on the level of danger have been fuzzy. Now the Nurses’ Health Study offers a more fine-grained assessment: even modest levels of alcohol consumption increase a woman’s risk of breast cancer a bit. In the study, 105,000 women were questioned about diet, lifestyle and health every few years for more than two decades. Nearly 7,700 cases of breast cancer were diagnosed in these women during that time.
Women who drank 3 to 6 glasses of wine weekly, less than a glass a day, had a 15 percent increase in their relative risk of cancer diagnosis compared to women who did not drink at all. But women who consumed two drinks or more a day saw their chance of breast cancer rise by 50 percent. The researchers suggest that alcohol seems to raise estrogen levels in women’s bloodstreams, which might account for the connection. The investigators acknowledge that women will need to weigh the influence of alcohol on promoting breast cancer against its beneficial effects in preventing heart disease.

[JAMA, Nov. 2, 2011]