Research Summary

GLP-1 Use Associated With Lower Breast Cancer Incidence

Ashton L. Stahl

Key Highlights

  • GLP-1 exposure was associated with lower breast cancer incidence in a retrospective cohort of women undergoing breast imaging.
  • The abstract included 94,827 women aged 45 to 80 years with a BMI greater than 25 and documented imaging outcomes.
  • In matched analysis, GLP-1 exposure before the exam date was associated with lower breast cancer incidence.
  • The authors stated that prospective trials are needed to investigate incretin medications for breast cancer prevention.

Results from a retrospective cohort study presented at the 2026 American Society of Clinical Oncology Annual Meeting and published in JCO Oncology Practice found that women exposed to GLP-1 receptor agonists before breast imaging had a lower incidence of breast cancer than women without documented GLP-1 exposure. The study addressed an unresolved question in breast cancer prevention: whether GLP-1 agonist use is associated with breast cancer risk among women eligible for breast cancer screening. The authors noted that excess weight is a key modifiable risk factor for breast cancer and that GLP-1 receptor agonists promote weight loss and improve markers of metabolic health.1

“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,” Elizabeth McDonald, MD, PhD, professor of Radiology in the University of Pennsylvania Perelman School of Medicine and a practicing breast radiologist at Penn’s Abramson Cancer Center, said in a press release.2

Researchers conducted a retrospective, time-dependent cohort study using electronic health records from January 1, 2022, to June 30, 2025. They identified 217,025 unique patients who underwent breast imaging and restricted the analytic sample to women aged 45 to 80 years with a BMI greater than 25 and a documented imaging outcome. In the abstract, the final cohort included 94,827 women, with a median age of 61 years.1

The primary outcome was breast cancer detection. GLP-1 use was defined as a first prescription before the breast imaging exam date. Researchers assessed GLP-1 exposure in relation to race, ethnicity, age, and type 2 diabetes and performed one-to-one case-control matching using propensity scores based on age, race, ethnicity, highest BMI, breast density, and type 2 diabetes diagnosis.1

Study Findings

Among 94,827 women in the study, 2,314 patients, or 2.4%, were diagnosed with breast cancer during the study period, while 92,513, or 97.6%, were not. Overall, 15,107 women (15.9%) had GLP-1 exposure, and 79,720 (84.1%) had no GLP-1 exposure. Of the women exposed to GLP-1 medications, 249 (1.65%) developed breast cancer compared with 2,065 (2.6%) who were among those without GLP-1 exposure. GLP-1 exposure was associated with lower breast cancer incidence in the overall analysis (OR, 0.630; 95% CI, 0.552-0.720; P < .0001). In the matched logistic regression analysis, which included 30,214 observations and 581 cancer cases, GLP-1 exposure before the exam date was also associated with lower breast cancer incidence (OR, 0.746; 95% CI, 0.632-0.880; P < .0005).1

In a related Penn Medicine electronic health record analysis of 111,646 women aged 45 to 80 years with a BMI of 25 or higher, breast imaging, and a documented outcome, 15,264 women had documented GLP-1 prescriptions, and 96,382 had no documented GLP-1 exposure. Lower breast cancer incidence was reported in both the full analysis and the matched cohort.2

Clinical Implications

According to the study authors, the findings support the need for prospective trials evaluating incretin medications for breast cancer prevention. They are working to develop a multisite clinical trial to assess whether GLP-1 medications can lower breast cancer incidence among high-risk women, including those with a history of breast cancer.

Additionally, the observational study did not definitively confirm an association between GLP-1 medications and reduced breast cancer incidence. It also noted that the study did not account for GLP-1 medication type or length of use, genetic risk factors, or cancer stage or type at diagnosis.2

Expert Commentary

“In this large observational study of women undergoing breast imaging at a major academic center, GLP-1 treatment was associated with a significantly lower incidence of breast cancer after accounting for age, race, ethnicity, BMI, breast density, and type 2 diabetes status, supporting the need for prospective trials investigating incretin medications for breast cancer prevention,” the researchers concluded.1

Reference

  1. McDonald ES, Gillis L, Gabriel P, Xapakdy K, Young AJ, Schnall MD, Pisano E. Association of GLP-1 agonists with breast cancer incidence in women. J Clin Oncol. 2026;44(suppl 16):10506. doi:10.1200/JCO.2026.44.16_suppl.10506
  2. Perelman School of Medicine at the University of Pennsylvania. GLP-1 use linked to lower breast cancer incidence in large cohort study. Newswise. Published May 29, 2026. Accessed June 2, 2026. https://www.newswise.com/articles/glp-1-use-linked-to-lower-breast-cancer-incidence-in-large-cohort-study.