Dr. Wendy Y. Chen of Brigham and Women's Hospital and Harvard Medical School in Boston and colleagues examined the association of breast cancer with alcohol consumption in adult life, including quantity, frequency and age.
The study involved 105,986 women enrolled in the Nurses' Health Study who were tracked from 1980 to 2008. There were 7,690 cases of invasive breast cancer diagnosed among the study participants.
The study, published in the Journal of the American Medical Association, found analyses of data indicated a low level of alcohol consumption -- three to six glasses of wine per week -- was modestly but statistically significant and associated with a 15 percent increased risk of breast cancer. In addition, women who drank at least two drinks per day had a 51 percent increased risk of breast cancer compared with women who never consumed alcohol, the study said.
Chen said alcohol consumption levels at ages 18-40 and after age 40 were both strongly associated with breast cancer risk.
"An individual will need to weigh the modest risks of light to moderate alcohol use on breast cancer development against the beneficial effects on cardiovascular disease to make the best personal choice regarding alcohol consumption," Chen said.