An observational study presented by the University of Pennsylvania Perelman School of Medicine’s Elizabeth McDonald, MD, PhD at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 10506) suggests a connection between GLP-1 medications and lower breast cancer risk. The findings are summarized in a press release.
Dr. McDonald emphasized that this study does not confirm the association, but more studies are needed. The study’s researchers investigated medical records from a total of 111,646 women classified as “overweight” and aged 45-80. Just under 14% had a prescription for GLP-1. The scientists found that the women with GLP-1 prescriptions had a 30.5% lower chance of being diagnosed with breast cancer. Penn Medicine noted that the following aspects were not taken into account: type of GLP-1 medication and how long the patient was on it, genetics, and cancer details. “Further analyses are planned to address some of these variables,” they said.
The researchers attribute their findings to the fact that GLP-1 addresses a key risk factor for breast cancer, being overweight. Additionally, “GLP-1s reduce systemic inflammation through several different pathways and have other metabolic and epigenetic effects that could inhibit tumor growth.”
