GLP-1 use linked to lower breast cancer incidence in large cohort study
A new Penn Medicine study sets the stage for a multisite clinical trial to determine whether GLP-1 drugs are associated with a lower risk of developing breast cancer.
2 min. read
A retrospective analysis of more than 110,000 women between the ages of 45 and 80 found that those who take GLP-1 medications are about 30% less likely to develop breast cancer than those who do not take GLP-1 medications. This is according to new research presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting by Elizabeth McDonald, a professor of radiology in Penn’s Perelman School of Medicine and a practicing breast radiologist at Penn’s Abramson Cancer Center. The findings are published in JCO Oncology Practice.
“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,” McDonald says.
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. Originally used to treat type 2 diabetes, GLP‑1 medications are now also widely used for weight management. A handful of recent observational studies have linked GLP-1s to lower cancer risks and/or improved outcomes in cancer survivors, but prospective data—the gold standard in clinical research—is lacking. Now, McDonald and collaborators are actively working to stand up 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,” McDonald says.
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