CAN ALCOHOL RAISE THE RISK OF BREAST CANCER?
Over the years countless studies have shown that moderate consumption of alcohol has myriad potential health benefits. Of course, this is often countered by studies indicating the detrimental effects of drinking. The recent results of a long-term study would seem to support an associated risk between breast cancer and alcohol consumption. Researchers found that women who regularly drink a small amount of alcohol – less than a drink a day – could increase their lifetime risk of breast cancer. Dr. Wendy Chen, assistant professor of medicine at Harvard Medical School and Brigham and Women’s Hospital, and her colleagues reported in the journal of the american medical association (jama) that women who consumed as little as three to six drinks a week over several decades were 15% more likely to develop breast cancer than women who didn’t drink at all. Heavier drinking, (at least two drinks per day) was associated with a 51% increase in risk. The effect was cumulative, with the risk of breast cancer rising 1O% with each 1O gram (about a third of an ounce) increase in alcohol consumption per day. However, this doesn’t mean that women need to dump out their glasses of wine. It wasn’t a huge effect – about 15 percent higher risk among drinkers compared with teetotalers. For example, even among women who sipped three to six glasses of wine per week, only 3.3 percent would develop breast cancer over 1O years. That compares to 2.8 percent of abstainers and 3.5 percent of women having up to 13 drinks a week. Second, there is still no ironclad proof that alcohol itself is to blame, even though the researchers did their best to rule out competing explanations such as smoking or older age. They also adjusted for other influences on breast cancer risk, like whether or not a woman has had children and breastfed.
The current research involved more than 1O5,OOO women enrolled in the long-running Nurses’ Health Study. The participants were asked about their alcohol consumption every four years between 198O and 2OO8. While other analyses have asked women only about their recent drinking habits, Chen’s decades-long investigation allowed her team to track drinking patterns over time, offering stronger data on the cumulative effect of alcohol on breast cancer. Even after adjusting for other factors that contribute to breast cancer, such as age, weight, smoking, and family history of the disease, the relationship between alcohol consumption and breast cancer remained. The connection was also strongest in women who reported drinking more either early or late in life, suggesting that women may be more vulnerable to the effects of alcohol on breast tissue during those periods.
Exactly how alcohol may trigger tumors isn’t clear, but experts theorize that it activates estrogen production in the body; higher circulating levels of the hormone can promote breast cell growth. That theory seems to be supported by other data from Chen’s study: most of the breast cancers diagnosed in the study’s participants were positive for the estrogen receptor, meaning that the tumors were driven by and dependent on the hormone. Chen’s study linked breast cancer to the same level of consumption that is commonly suggested to reduce the risk of heart disease. Having a few drinks a week could lower the risk of heart disease by 25% to 4O%; for the average 5O-year-old woman, the risk of heart disease is 39%. For many women it may come down to weighing the risks of heart disease versus breast cancer.