GLP-1 drugs (Ozempic, Mounjaro) reduce breast cancer risk by 30%

Scientists from the University of Pennsylvania Perelman School of Medicine analyzed data from more than 111,000 women who initiated therapy with GLP-1 medications. Compared to the control group, those who took these drugs had approximately a 30% lower risk of developing breast cancer. The association persisted even after adjusting for age, body mass index, breast tissue density, and other known risk factors.

“This is the first large-scale study demonstrating the potential protective effect of GLP-1 medications against breast cancer,” the authors noted.

The exact mechanism has not yet been established, but scientists suggest that reduced chronic inflammation, improved metabolism, and decreased adipose tissue may play an important role. A direct effect on GLP-1 receptors present in breast tissue is also possible.

It is important to understand that the study is observational, meaning it shows an association rather than a strict causal relationship. Nevertheless, the results appear promising and warrant further investigation in randomized clinical trials.

The work was presented at the annual meeting of the American Society of Clinical Oncology (ASCO) and published in JCO Oncology Practice.

Sources:

1. Elizabeth S. McDonald et al. GLP-1 Receptor Agonist Use and Breast Cancer Risk in Women with Obesity and Diabetes. JCO Oncology Practice, 2026.
2. Press release from the University of Pennsylvania and ScienceDaily (May 26, 2026).