Research has consistently shown that regularly drinking alcohol increases a woman's risk of breast cancer, particularly hormone-receptor-positive breast cancer. Results from a new study support the connection between risk and regular drinking.
The study was published in the Nov. 2, 2011 issue of the Journal of the American Medical Association (JAMA).
The study used information from the very large and ongoing Nurses' Health Study (NHS). Nearly 122,000 female nurses were between the ages of 25 and 42 when they joined the NHS in 1976. The NHS is tracking lots of information about diet, lifestyle, and health, including breast cancer diagnoses.
In 1980, the researchers started asking the women in the NHS about their drinking habits; by the middle of 2008, the researchers had nearly 30 years of information. Also by the middle of 2008 7,690 cases of invasive breast cancer had been diagnosed in the women. The researchers looked for links between drinking habits and breast cancer risk. They found that the more alcohol consumed (the type of alcohol didn't matter), the greater breast cancer risk:
- Women who had about three to six alcoholic drinks a week had a 15% higher risk of breast cancer compared to women who didn't drink.
- Women who had more than 30 drinks a week had a 50% higher risk of breast cancer compared to women who didn't drink.
The amount a woman drank was more tightly linked to breast cancer than how often a woman drank. In other words, binge drinking (drinking a lot of alcohol now and then) increased risk much more than regularly drinking small amounts of alcohol.
This and other studies found that risks for cardiovascular problems (heart attack or stroke) were lower for women who drank alcohol regularly. So when making decisions about drinking and health, it's reasonable to consider the balance between higher breast cancer risk and lower cardiovascular risk.
The increase in breast cancer risk related to alcohol in this study is a little smaller than the results of other studies. For example, results from a very large research study (the Million Women Study) published in 2009 in the Journal of the National Cancer Institute estimated that breast cancer risk goes up with as few as three drinks per week and that each daily drink increases breast cancer risk by about 12%. So compared to a woman who doesn't drink:
- a woman who has one drink per day has about a 12% higher risk of breast cancer
- a woman who has two drinks per day has about a 24% higher risk of breast cancer
An article in the Nov. 1, 2011 Wall Street Journal online discussed a study published in the Nov. 1, 2011 issue of the American Journal of Epidemiology on the link between many different types of cancer and drinking alcohol. The Wall Street Journal article concluded that regularly drinking alcohol, even in moderation, raises the risk of many kinds of cancer, including breast cancer.
Breastcancer.org Chief Medical Officer Marisa Weiss, M.D., discusses alcohol, breast cancer risk, and the Wall Street Journal article in her Nov. 9, 2011 Think Pink, Live Green Expert Column.
It's not clear why drinking alcohol increases breast cancer risk. Many studies have shown that hormone-receptor-positive breast cancer is most affected by alcohol. Estrogen can cause hormone-receptor-positive breast cancer to grow and alcohol can increase the amount of estrogen in a woman's body. This estrogen increase may partly explain the link.
The results of the studies discussed here support the results of many other large studies linking alcohol and breast cancer risk. Many of these studies suggest that drinking any amount of alcohol regularly seems to increase cancer risk. If you want to do everything you can to lower your risk of breast cancer (or breast cancer coming back), drinking two drinks or fewer per week makes sense.
Regularly drinking alcohol is a habit that often starts in early adulthood. You might want to talk to your daughters, granddaughters, and other young women in your life about the link between alcohol and breast cancer risk.
To learn more about how you can keep your risk of breast cancer as low as it can be, visit the Breastcancer.org Lower Your Risk section.