GLP-1 Weight Loss Drugs Linked to Lower Breast Cancer Risk, Study Finds

Researchers at Penn Medicine found that women who took GLP-1 drugs had a lower observed risk of breast cancer compared to women who did not use the medications. The study, published in June 2026, analyzed electronic health records from women with a body mass index of 25 or higher.

GLP-1 drugs, which include semaglutide medications sold under the brand names Ozempic and Wegovy, were originally developed to treat type 2 diabetes. They have become widely used for weight loss over the past several years.

The Penn Medicine team compared breast cancer rates between GLP-1 users and non-users over a multi-year period. Women taking the drugs showed a lower rate of breast cancer diagnoses. The researchers said the association may be related to the drugs' effects on weight, inflammation, or insulin levels, all of which are known to influence cancer risk.

The study was observational, meaning it tracked outcomes in existing patient records rather than randomly assigning participants to treatment groups. The researchers said the design limits their ability to establish a direct cause-and-effect relationship. Other factors, such as differences in health behaviors between GLP-1 users and non-users, could explain part of the difference.

The findings add to a growing body of research on the potential health benefits of GLP-1 drugs beyond blood sugar control and weight loss. Earlier studies have linked the medications to reduced risk of heart disease and lower rates of certain other cancers.

Doctors said the results are promising but that patients should not start taking GLP-1 drugs specifically to reduce cancer risk until more research is available.