Women who take drugs like Ozempic have lower breast cancer risk: study

By Stephen Beech

Women who take popular weight loss drugs such as Ozempic and Wegovy reduce their risk of breast cancer by almost a third, suggests new research.

GLP-1 medicines are linked to a 30% lower chance of developing the potentially deadly disease, say American scientists.

A retrospective analysis of more than 110,000 women between the ages of 45 and 80 found that those who took GLP-1 medications, such as Ozempic or Wegovy, were around 30% to 35% less likely to develop breast cancer than those who didn't.

Elizabeth McDonald, of the University of Pennsylvania Perelman School of Medicine, said: "While our study was observational and does not definitively confirm an association between GLP-1 medications and reduced breast cancer incidence, it does add to the growing body of evidence suggesting that it's worth investigating these weight-loss drugs as potential cancer prevention tools."

GLP-1 medications are a class of drugs that mimic a natural hormone in the body called glucagon-like peptide-1, which helps regulate blood sugar and appetite.

Originally used to treat type 2 diabetes, GLP-1 medications are now also widely used for weight management.

A handful of recent observational studies have linked GLP-1s to lower cancer risks or improved outcomes in cancer survivors.

But prospective data — the "gold standard" in clinical research — was lacking.

Now, McDonald and her team are working to stand up a multi-site clinical trial to assess whether GLP-1 medications can lower breast cancer incidence among women at high risk, including those with a history of breast cancer.

McDonald, who is also a practicing breast radiologist, said: "GLP-1 medications are intriguing from a cancer research perspective because they weren't designed for cancer therapy.

"But they do affect many different targets and pathways associated with cancer development, so we're eager to study them in this context."

The research team looked at health records from 111,646 women, aged 45 to 80, with a body mass index (BMI) of 25 or above — classified as "overweight" — who had breast imaging and a documented outcome between January 2022 and June 2025.

Of the women, 13.7% had documented GLP-1 medication prescriptions, while the other 86.3% had no documented exposure to GLP-1 medications.

The research team then looked at whether women were diagnosed with a new breast cancer in two different groupings: the full group of 111,646 women and a smaller cohort of 30,528 women, including one-to-one controls for each of the 15,264 GLP-1 cases, matched across age, race, ethnicity, BMI, breast density, and diabetes status to limit bias.

The lower incidence of breast cancer was seen across both groups: 35.1% lower odds in the full analysis and 30.5% lower odds in the matched cohort.

The study did not account for type of GLP-1 medication or length of use, genetic risk factors, or cancer stage or type at diagnosis. Further analyses are planned to address some of these variables.

McDonald said GLP-1 medications are highly effective at helping people lose weight, and maintaining a healthy weight has long been recommended as part of breast cancer prevention strategies because being overweight or obese, particularly after menopause, is a known breast cancer risk factor.

Researchers have also long suspected that low-grade inflammation may play a role in breast cancer development.

McDonald says GLP-1s reduce systemic inflammation through several different pathways and have other metabolic and epigenetic effects that could inhibit tumor growth.

The researchers currently suspect that the multiple effects of GLP-1 medications inhibit breast cancer development.

They say that while the drug tamoxifen is "highly effective" at reducing breast cancer incidence in high-risk patients, uptake among eligible patients is limited, due to the drug's known side effects.

But GLP-1 medications are already widely used by millions of people.

McDonald added: "Ultimately, we want to find better options to prevent breast cancer.

"It's been encouraging to see the survival rates for breast cancer improve over recent decades, and we'd love to see the same gains in prevention."

She presented the findings at the annual meeting of the American Society of Clinical Oncology (ASCO) in Chicago, Illinois.

The findings were also published in the journal JCO Oncology Practice.