Research published in the latest issue of the Journal of the American Medical Association found that as few as 3 to 6 glasses of wine per week increased a woman’s chance of developing breast cancer. The risk of breast cancer also rose based on the amount of alcohol consumed cumulatively throughout her lifetime.
Wendy Y. Chen, MD, MPH, of Brigham and Women’s Hospital and Harvard Medical School, Boston, led the study examining the relationship between breast cancer and alcohol consumption during adult life. Specific lifestyle factors included quantity and frequency of alcohol consumption, plus the age at which alcohol was consumed. Chen and her colleagues used data from The Nurses’ Health Study and followed 105,986 women from 1980 until 2008. Patient evaluations included an early adult alcohol assessment and 8 updated alcohol assessments.
There were 7690 cases of invasive breast cancer diagnosed during the follow-up evaluations. Data analysis revealed that a low level of alcohol consumption, approximately 3 to 6 glasses of wine per week, was associated with a 15% increased risk of breast cancer. Furthermore, compared with women who never consumed alcohol, those women who consumed at least 2 drinks per day had a 51% increased risk of breast cancer. The study found no increased risk for breast cancer among women who drank less than the equivalent of 3 glasses of wine per week.
When the amount of alcohol in wine, beer, and liquor was considered, results showed no difference in cancer risk among the beverages.
Additionally, the study showed alcohol added to whatever existing risk a woman already possessed for breast cancer. For instance, a woman with a family history of breast cancer would add to that risk if her lifestyle included higher alcohol consumption.
Chen and colleagues also found alcohol consumption between the ages of 18 and 40 years and after age 40 years were both significantly related to breast cancer risk. Even upon controlling alcohol intake after age 40, the association with drinking in early adult life still endured. Furthermore, after controlling for cumulative alcohol intake, binge drinking was also associated with breast cancer risk.
Although the exact mechanism causing the association between alcohol consumption and breast cancer is unknown, researchers suggest one probable explanation may involve the effect of alcohol on circulating estrogen levels.