Reviewed by - A large retrospective study analyzed over 100,000 women and observed that those on GLP-1s were up to 35% less likely to develop breast cancer.
- Experts say the link may be driven by weight loss and resulting metabolic changes from the use of GLP-1 medications.
- The findings don’t prove that GLP-1s prevent breast cancer and only show an association—but still, the link is significant enough that more research is needed.
There’s been a flood of research that suggests GLP-1 medications like Ozempic and Zepbound can lower your risk of developing a slew of serious illnesses or help to turn things around if you already have a diagnosis. Now, a large new scientific analysis is adding one more disease that GLP-1s may unintentionally help with: breast cancer.
The link between medications that are typically used to treat type 2 diabetes or obesity and breast cancer might seem a little random, but doctors say it’s not as out-there as you’d think. Here’s why experts say this is notable, what the new research suggests for the future of breast cancer prevention, and everything else you need to know.
Meet the expert: Gilberto Lopes, MD, chief of the division of Medical Oncology with Sylvester Comprehensive Cancer Center, part of the University of Miami Health System; Elizabeth McDonald, MD, PhD, lead study author and professor of Radiology at the Hospital of the University of Pennsylvania; Amy Bremner, MD, Breast Surgical Oncologist and medical director of Breast Surgical Oncology at MemorialCare Saddleback Medical Center in Laguna Hills, California.
What Did the Study Find?
The study, which was published in JCO Oncology Practice, analyzed health records from nearly 112,000 women between the ages of 45 and 80 with a body mass index (BMI) of 25 or higher. (A BMI of 25 or higher is considered the threshold for being classified as “overweight.”) These participants underwent breast imaging and their outcome data was documented between January 2022 and June 2025.
Among the study participants, 15,264 (13.7 percent) had prescriptions for GLP-1 medications, while 96,382 (86.3 percent) had no documented prescriptions for GLP-1 medications.
Researchers analyzed two different cohorts: the nearly 112,000 women previously mentioned and a smaller group of 30,528 women, with one-to-one controls for people who took GLP-1 medications. One-to-one controls meant that each woman was matched to another woman of the same age and race, with the same BMI, and who shared other factors besides being on a GLP-1.
In both groups, women who used a GLP-1 medication had a significantly lower risk of being diagnosed with breast cancer. In the larger analysis, women on a GLP-1 had a 35.1 percent lower chance of being diagnosed with breast cancer. In the smaller, one-to-one group, they had a 30.5 percent lower risk.
Ultimately, researchers concluded that “GLP-1 treatment was associated with a lower incidence of breast cancer, independent of age, race, ethnicity, BMI, breast density, and diabetes.”
Why Would GLP-1s Have This Effect?
The research didn’t study why these medications would have this effect or even prove that GLP-1 medications lowered the risk of breast cancer; rather, it simply found an association between being on a GLP-1 and a lower likelihood of developing breast cancer.
All of that said, the link is “not surprising”—to doctors, at least, says Amy Bremner, MD, breast surgical oncologist and medical director of Breast Surgical Oncology at MemorialCare Saddleback Medical Center in Laguna Hills, California.
There are likely several reasons why this may be the case, according to Gilberto Lopes, MD, chief of the division of Medical Oncology with Sylvester Comprehensive Cancer Center, part of the University of Miami Health System. “The biggest is likely weight loss,” he says.
“After menopause, body fat becomes a woman’s main source of estrogen, and estrogen fuels the most common type of breast cancer,” Dr. Lopes says. “Less fat means less estrogen.”
Elizabeth McDonald, MD, PhD, lead study author and professor of Radiology at the Hospital of the University of Pennsylvania, agrees that weight likely plays a big role in this link. “GLP-1 agonists reduce weight, and weight alone is a risk factor for breast cancer,” she says.
There’s a range of data to support this, but one scientific analysis found that post-menopausal women with obesity have a nearly 30 percent greater chance of developing breast cancer than women who are classified as having a normal weight.
GLP-1s also lower insulin resistance—a condition where your body does not respond to insulin as it should—which in turn lowers a growth signal called IGF-1. Both of these can push tumors to grow, Dr. Lopes says. “They quiet the chronic inflammation that comes with carrying extra weight,” he adds.
There’s also the possibility that GLP-1 medications may even directly impact breast cancer risk, Dr. Lopes says, given that some breast tumors carry the GLP-1 receptor on their surface.
Could This Help People Who Aren’t Overweight or Obese?
That’s not clear yet. “We don’t have this information, although our observational data did look at women who are overweight and non-obese,” Dr. McDonald says.
But Dr. Lopes says GLP-1s probably won’t help to the same degree in people who aren’t overweight or obese. “Most of the benefit likely flows through weight loss and the metabolic changes that follow it,” he says. “A lean woman with normal estrogen and normal insulin has less for the drug to correct, so there’s less to gain.”
As for whether GLP-1s will be used to prevent breast cancer in the future, Dr. Lopes says it’s possible. “We already do this with drugs like tamoxifen, which healthy high-risk women take to lower their odds, so a preventive medication isn’t a new idea,” he says. For now, Dr. Lopes says the idea of preventive GLP-1 use for breast cancer probably makes the most sense for women who have both elevated breast cancer risk and a reason to lose weight, “where the benefit and the need line up.” However, Dr. Lopes adds that we’ll need randomized controlled trials in the future for further insight.
Photographs: Julia Gartland
Prop Styling: JoJo Li
Carina Hsieh, MPH, is the deputy features editor of Women’s Health. She has more than a decade’s worth of experience working in media and has covered everything from beauty, fashion, travel, lifestyle, pets, to health.
She began her career as an intern in the fashion closet at Cosmopolitan where she worked her way up to Senior Sex & Relationships Editor. While covering women’s health there, she discovered her passion for health service journalism and took a break to get her Masters in Public Health. Post-grad school, she worked as a freelance writer and as The Daily Beast’s first Beauty, Health, and Wellness Reporter.
Carina is an alum of the Fashion Institute of Technology and the Yale School of Public Health. She and her French Bulldog, Bao Bao, split their time between Brooklyn and Connecticut. She enjoys reformer Pilates, (slow) running, and smelling the fancy toiletries in boutique fitness class locker rooms.
