4 Updates on Alcohol and Breast Cancer Risk From SABCS 2025

For decades, researchers have known that drinking alcohol raises the risk of breast cancer. But only recently have they started to understand the details.

“Almost all studies find that women who drink at least a drink per day, or maybe a little bit less, have an increased risk of breast cancer,” said Julie Palmer, ScD, during a session at the 2025 San Antonio Breast Cancer Symposium. Palmer is a cancer epidemiologist at Boston University. 

The speakers shared recent updates about how drinking alcohol affects breast cancer risk. Here are four of the most important findings.

Studies suggest that there is no “safe” amount of alcohol when it comes to breast cancer risk. That’s because alcohol causes DNA damage, inflammation, and oxidative stress — which can trigger cancer growth. Alcohol also raises levels of the hormone estrogen, which especially raises the risk of estrogen receptor-positive breast cancer.

A review using data from 20 studies found that people who have fewer than three drinks per week have a higher breast cancer risk than those who don’t drink at all. But the size of this increased risk is small.

The findings were based on how much people said they drank, and people tend to underestimate this. So more research is needed. 

People used to think that only certain types of alcohol posed a cancer risk. In particular, they thought red wine didn’t raise cancer risk because it’s branded as healthy, especially for the heart, because it contains antioxidants. But newer research has shown that all types of alcohol raise breast cancer risk. A study of more than 70,000 people found no difference in breast cancer risk between people who drank liquor, beer, wine, or red versus white wine. 

Researchers are just starting to learn how stopping drinking affects risk. If you’ve been drinking for years — even decades — and then quit, your risk of some breast cancers may go down. 

Some studies suggest that women who quit drinking alcohol are at lower risk of estrogen receptor-positive but not estrogen receptor-negative breast cancer. This is likely because quitting alcohol lowers levels of estrogen in the body, said Mary Beth Terry, PhD, an epidemiologist at Columbia University, during the session. But more research is needed to test this theory. Most studies that look at what quitting does to the body have been in men with alcohol use disorder, in which drinking too much causes symptoms such as dependence.

There isn’t enough data to say how drinking less affects breast cancer risk. Even so, experts recommend cutting back on your alcohol intake if stopping completely doesn’t feel doable.

Binge drinking may be especially harmful when it comes to breast cancer risk, and is a unique risk factor separate from regular drinking, Palmer said. For women, binge drinking is officially defined as having four or more drinks in a couple hours, at least once per month. But some studies use different criteria, like having six or more drinks at one time. Binge drinking is harmful even if you don’t drink on a daily or weekly basis.

An increase in binge drinking among women in their 30s and 40s could partly explain a rise in early-onset breast cancer. A study Terry worked on that was published last year, for instance, found that binge drinking is linked to a higher rate of early-onset luminal A breast cancer but not early-onset HER2-positive or triple-negative breast cancer. Using one method of analysis, the researchers found that binge drinking was linked to higher rates of luminal B breast cancer; using another method, they did not. So, the link between binge drinking and luminal B breast cancer isn’t clear. More research is needed to confirm the link between binge drinking and different types of early-onset breast cancer.

During the session, patient advocate Stacey Tinianov described how people want real steps they can take to lower their breast cancer risk. While there are some risk factors for breast cancer that you can't control, such as your age or DNA, changing how much alcohol you drink may help to lower your risk of breast cancer.