Could GLP-1 drugs help prevent breast cancer? New study points to a possible link

A major breast imaging study links GLP-1 agonists to lower breast cancer incidence, raising hopes for a new prevention strategy while underscoring the need for prospective clinical trials.

Study: GLP-1 Agonists Are Associated With a Significant Reduction in Breast Cancer Incidence in Women. Image Credit: Love Employee / Shutterstock

The findings were consistent after accounting for age, race, ethnicity, body mass index (BMI), breast density, and diabetes. Women using GLP-1 agonists showed lower odds of developing breast cancer compared with those who did not use these drugs. In fact, in this study, less than two percent of women with GLP-1 exposure were diagnosed with breast cancer.

Obesity is an important modifiable risk factor for breast cancer. In other words, sustained weight loss may help reduce breast cancer risk in some populations. Scientists have found that GLP-1 agonists can help reduce body weight and enhance metabolic regulation. They are also increasingly finding that these drugs may help reduce inflammation, a hallmark of cancer. Whether GLP-1 agonists can also reduce breast cancer risk, however, remains unclear. This is because previous studies focused on women with higher BMI since they are most likely to be prescribed GLP-1 agonists.

Study Design

In the present study, researchers evaluated the association between GLP-1 agonist use and breast cancer incidence. They analyzed electronic medical records of the University of Pennsylvania Health System between January 2022 and June 2025.

These records included more than 217,000 women who underwent breast imaging. For the present analysis, the team selected a subset of 111,646 overweight and obese women (BMI ≥25, median age 61 years) aged 45-80 years. Breast imaging results were available for these individuals.

GLP-1 Use and Lower Incidence

The study included 111,646 overweight and obese women. In this sample population, 15,264 individuals (14%) used GLP-1 agonists, whereas 96,382 individuals (86%) did not use these medications. Among women taking GLP-1 agonists, less than two percent (n=247) received a breast cancer diagnosis.

In the unmatched analysis, GLP-1 agonist use was linked to lower breast cancer incidence (OR, 0.65). After matching, the analysis included 30,528 observations and 600 breast cancer cases. Researchers found similar results.

Early studies suggest that GLP-1 agonists, such as exenatide and liraglutide, may reduce breast cancer cell proliferation and viability by altering cellular energy metabolism. In mouse models, scientists found that drugs such as tirzepatide, which act on both glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 receptors, could reduce tumor growth.

However, the researchers emphasized that the study was observational and hypothesis-generating. The analysis could not determine whether GLP-1 agonists directly reduced cancer incidence, nor could it assess medication adherence, dose, treatment duration, cumulative exposure, or the effects of different drug formulations. Some women classified as unexposed may also have received GLP-1 medications outside the health system.

Breast Cancer Prevention 

The findings demonstrate that GLP-1 users had nearly 30% lower odds of being diagnosed with breast cancer. These effects were similar in magnitude to risk reductions observed with tamoxifen in early studies, although this comparison reflects effect size rather than equivalent evidence strength or clinical readiness.

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Journal reference:

• Elizabeth S. McDonald et al. (2026). GLP-1 Agonists Are Associated With a Significant Reduction in Breast Cancer Incidence in Women. JCO Oncology Practice, 10.1200/OP-26-00485. DOI: 10.1200/OP-26-00485, https://ascopubs.org/doi/10.1200/OP-26-00485