Could GLP-1 Medications Like Ozempic Lower Breast Cancer Risk?

Recent research indicates that women taking GLP-1 medications—a class of drugs including semaglutide and tirzepatide—may have a significantly lower likelihood of developing breast cancer. A study of over 110,000 women found that those using these medications showed approximately a 30% reduction in breast cancer incidence compared to non-users, according to findings presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and published in JCO Oncology Practice.

What the Research Says

The study, conducted by researchers at the University of Pennsylvania Perelman School of Medicine, analyzed electronic health records for 111,646 women between the ages of 45 and 80. All participants had a body mass index (BMI) of 25 or higher and had undergone breast imaging within the Penn Medicine health system between January 2022 and June 2025.

According to the data, 15,264 women had documented prescriptions for GLP-1 medications, while 96,382 did not. When researchers compared the full study population, women taking GLP-1 drugs showed a 35.1% lower risk of a new breast cancer diagnosis. In a secondary analysis that matched users with non-users based on age, race, BMI, breast density, and diabetes status, the risk reduction remained notable at 30.5%.

Elizabeth McDonald, MD, PhD, a professor of Radiology at the University of Pennsylvania Perelman School of Medicine and a practicing breast radiologist at Penn’s Abramson Cancer Center, noted that while the study is observational and cannot definitively prove cause and effect, the findings warrant further investigation into these drugs as potential cancer prevention tools.

How GLP-1 Drugs May Affect Cancer Risk

GLP-1 medications, which include widely used brands like Ozempic, Wegovy, Mounjaro, and Zepbound, were originally developed to manage type 2 diabetes by mimicking the glucagon-like peptide-1 hormone. This hormone regulates appetite and blood sugar levels, leading to weight loss.

Because obesity is a well-established risk factor for breast cancer—particularly in postmenopausal women—the weight loss associated with these drugs is a primary area of interest. However, researchers are also investigating other biological pathways. According to the study authors, GLP-1 drugs may influence chronic low-grade inflammation, metabolic processes, and epigenetic factors that contribute to cancer development.

Future Clinical Trials

Because the current study was observational, it did not account for variables such as treatment duration, genetic risk factors, or specific tumor subtypes. To address these gaps, Dr. McDonald and her colleagues are working to launch a multisite clinical trial. This prospective research aims to determine whether GLP-1 medications can directly lower breast cancer incidence in high-risk women, including those with a previous history of the disease.

Current preventive options, such as prophylactic surgery or medications like tamoxifen, often come with significant side effects that lead many patients to decline them. Researchers hope that if these findings are confirmed in clinical trials, GLP-1 medications could offer a new, more appealing pathway for breast cancer prevention.

Key Takeaways

• Significant Findings: A study of 111,646 women found that GLP-1 medication use was associated with an approximately 30% lower likelihood of developing breast cancer.
• Observational Nature: While the results are promising, researchers emphasize that observational studies cannot confirm a direct cause-and-effect relationship.
• Mechanism of Action: Beyond weight loss, GLP-1s are being studied for their potential to reduce inflammation and affect metabolic pathways linked to cancer growth.
• Ongoing Research: A multisite clinical trial is currently in development to provide more definitive evidence regarding the protective effects of these drugs against breast cancer.

The study was supported by the American College of Radiology Center for Research and Innovation, the Pennsylvania Breast Cancer Coalition, and the Abramson Cancer Center.