Does alcohol increase the risk of breast cancer? Yes, even light to moderate drinking, according to a new analysis from the well-known Nurses’ Health Study, which followed 106,000 women for more than 25 years.
It found that women who routinely consumed threeto six drinks per week were 15 percent more likely to develop breast cancer than non drinkers, regardless of the type of alcoholic beverage they consumed. For women averaging six to 19 drinks per week, the increased risk was 20 percent. Among those consuming more than 19 drinks per week, the risk jumped by 50 percent.
Alcohol, in moderation, has gotten a healthy reputation because it helps prevent heart attacks (and possibly diabetes, dementia, osteoporosis and other disorders), so you may be surprised to hear that it can boost cancer risk.
In the past 15 years, accumulating evidence has strongly linked alcohol to a number of cancers, notably of the esophagus, mouth and throat, but also of the liver, colon and breast. It may contribute to breast cancer by raising blood levels of estrogen.
The studies on alcohol and breast cancer have mostly blamed heavy drinking. Many have not found significantly higher risk among light drinkers.
The new study, in the Journal of the American Medical Association, receivedlots of attention not only because it was large and comprehensive, but because it found that light or moderate drinkers also face increased risk. In addition, it concluded that lifetime alcohol consumption (starting in early adulthood), rather than current levels, was the best measure of risk.
Why it’s hard to prove the link
All studies of alcohol and cancer are observational. It would be very difficult to do clinical trials in which subjects are randomly assigned long-term alcohol consumption or abstinence. In the new study, researchers observed how many cases of cancer occurred in the women over the decades and matched these up with how much alcohol they consumed (based on self-reports, which can be unreliable).
They took into account factors such as age, weight, smoking, family history and hormone use. This type of research cannot prove cause and effect or precisely indicate where the risk thresholds lie, but it can be strongly suggestive.
Putting the risk into perspective
Any additional cancer risk is bad, of course, but a 15 percent increased risk (found for threeto six drinks a week in this study) is not as threatening as it may sound. At age 50, for instance, the average woman has a 2.4 percent chance (1 in 42) of developing breast cancer in the next 10 years. An increase of 15 percent would raise the risk to about 2.8 percent (1 in 37).
Stated another way, among 1,000 women age 50, light drinking may cause an extra three or fourcases of breast cancer during the next decade—which would presumably be more than offset by a reduction in heart attacks. Keep in mind, these are only averages. For women with a family history of breast cancer, for example, the estimated risks will be higher. For others, the risks may be lower.
- If you’re a woman and drink, should you quit to reduce your risk of breast cancer? Or should you continue to drink to help protect your heart, particularly if you’re at high risk for heart disease? Here are some pointers.
- If you drink, keep your intake light to moderate. For a woman, that means no more than a drink a day (for men, it’s two drinks). A standard drink is four to fiveounces of wine, 12 ounces of beer or 1.5 ounces of 80-proof liquor, which all contain about 14 grams of pure alcohol (ethanol). That’s all you need for heart health. And that limits the increase in cancer risk.
- If you know you are at high risk for breast cancer, or if you have had breast cancer, it may make sense to quit drinking or drink only occasionally. Discuss your risk factors for both breast cancer and heart disease with your doctor.
- If you are a light or moderate drinker at average risk for breast cancer, you may reduce the risk somewhat by giving up drinking—but nobody knows for sure.
- Be sure to consume enough folate, one of the B vitamins. Studies suggest that an adequate folate intake reduces the increased risk of breast cancer associated with alcohol. Leafy greens and citrus fruit are good sources; many grain products are fortified. A basic multivitamin provides the RDA (400 micrograms a day). Higher-dose supplements are not necessary or recommended. (An exception: Women who may become pregnant should take 400 to 800 micrograms of folic acid a day to help prevent birth defects).
Bottom line:Alcohol has many known harms as well as many known or potential benefits. An increased risk of breast cancer is only one factor to consider. Age is another. Women are far more likely to die from cardiovascular disease than breast cancer, especially later in life. So for older women, the benefits of light or moderate drinking are more likely to outweigh the risks.