A study strongly suggests that regularly drinking even small amounts of alcohol increases the risk of many types of cancer -- including breast cancer -- in women.
Earlier research has shown a link between drinking large amounts of alcohol and higher breast cancer risk. Most of this earlier research suggested that small amounts of alcohol didn't affect breast cancer risk very much.
Still, based on the results of the study reviewed here, the researchers concluded that there's NO amount of alcohol that's safe when it comes to cancer risk.
The study, called the Million Women Study, had 1.3 million middle-aged women living in England fill out two surveys: one when they joined the study and one 3 years later. The surveys asked the women how many alcoholic drinks they had each week. About 25% of the women didn't drink alcohol. The women who drank alcohol had about one drink per day.
The researchers then looked at the medical histories of the women for the next 7 years to see if there was a link between cancer risk and regularly drinking alcohol. Because the study was so large (more than 1 million women), the results are considered very credible:
- About 69,000 women developed some form of cancer.
- Cancer risk was lowest in the women who didn't drink alcohol.
- Women who drank were more likely to develop several types of cancer, including breast, liver, rectum, mouth, throat, and esophagus compared to women who didn't drink.
- The higher cancer risk was seen even in women who regularly drank only small amounts of alcohol.
- The researchers estimated 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
Researchers don't completely understand why drinking alcohol seems to increase breast cancer risk. Other studies have shown that hormone-receptor-positive breast cancer is the type of breast cancer 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 increase in estrogen may be part of the reason for the link between alcohol and breast cancer risk.
It's also worth noting that the women in this study self-reported how much they drank. It's unclear whether the women kept alcohol diaries so they had a written record to refer to or whether they simply relied on memory when filling out the two surveys. Depending on people's memories of what they ate or drank is a common way to do studies like this. Still, people sometimes think they ate or drank less than they actually did, which can influence the results.
The results of this study support the results of many other large studies linking alcohol to breast cancer risk. If you want to do everything you can to lower your risk of breast cancer (or breast cancer coming back), limiting your drinking makes sense. Based on the study reviewed here, drinking any amount of alcohol regularly seems to increase cancer risk.
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.