A major study has identified a potential link between some weight-loss medication and a lower risk of breast cancer.
An analysis of more than 110,000 women found those who took GLP-1 medications were about 30 percent less likely to develop breast cancer than those who did not.
GLP‑1 medications are a class of drugs that mimic a natural hormone in the body called glucagon‑like peptide‑1, which helps regulate blood sugar and appetite.
They were originally used to treat type 2 diabetes but are now also widely used for weight management.
The research findings were announced last week by the University of Pennsylvania Perelman School of Medicine at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting.
Radiology Professor Elizabeth McDonald said that the study was observational and did not definitively confirm an association between GLP-1 medications and reduced breast cancer incidence.
Professor McDonald and collaborators are seeking to establish a multisite clinical trial to assess whether GLP-1 medications can lower breast cancer incidence among women at high-risk, including those with a history of breast cancer.
“GLP-1 medications are intriguing from a cancer research perspective because they weren’t designed for cancer therapy, but they do affect many different targets and pathways associated with cancer development, so we’re eager to study them in this context,” she said.
For the latest research, the team reviewed health records from 111,646 women ages 45 to 80 with a body mass index (BMI) of 25 or above who had breast imaging and a documented outcome between January 2022 and June 2025.
Of those women, 15,264 (13.7 percent) had documented GLP-1 medication prescriptions, and 96,382 (86.3 percent) had no documented exposure to GLP-1 medications.
“Ultimately, we want to find better options to prevent breast cancer,” Professor McDonald said.
“It’s been encouraging to see the survival rates for breast cancer improve over recent decades, and we’d love to see the same gains in prevention.”
The full report is here.
