Wegovy and Zepbound Linked to Lower Breast Cancer Risk

Obesity raises the risk of breast cancer, one of the most common cancers among women in the United States. A large observational study now suggests that GLP-1 medications such as Wegovy and Zepbound, widely used for weight loss and diabetes, could be associated with a meaningful reduction in that risk. Researchers presented the findings at the American Society of Clinical Oncology meeting in Chicago and published them in JCO Oncology Practice.

Scale of the Research and Key Results

The analysis examined health records from more than 111,000 women aged 45 to 80 who were overweight and had undergone breast imaging at Penn Medicine facilities between 2022 and mid-2025. More than 15,000 of those women had received prescriptions for GLP-1 drugs, while the rest had no record of such prescriptions.

Women who took the medications showed a 35.1 percent lower risk of breast cancer diagnosis compared with those who did not. After researchers matched the groups for age, race, ethnicity, body mass index, breast density, and diabetes status, the reduced risk remained at 30.5 percent. The study did not distinguish between specific GLP-1 formulations or track how long women used the drugs.

Limitations That Temper the Findings

Because the work relied on existing medical records, it could not account for genetic risk factors or whether cancers had already advanced at diagnosis. Some women may have obtained GLP-1 medications outside the Penn system through telehealth or compounding pharmacies, which could have placed them in the control group and affected the results.

The observational design also means the study cannot prove that the drugs themselves prevent breast cancer. Other lifestyle or medical factors not captured in the records might explain part of the difference.

Supporting Evidence and Planned Follow-Up

Separate research released in May by investigators at Virginia Commonwealth University found that breast cancer patients with obesity or Type 2 diabetes who used GLP-1 drugs had higher survival rates after ten years and lower rates of tumor recurrence. Those results align with earlier observations that intentional weight loss improves outcomes for breast cancer survivors.

Dr. Elizabeth McDonald of the University of Pennsylvania noted that the combined findings increase the likelihood of a genuine biological effect worth testing in a randomized clinical trial. Researchers are now seeking funding for a five-year study that would evaluate whether GLP-1 drugs can reduce new breast cancers in high-risk women and lower recurrence in those who have already been treated.

GLP-1 medications already carry approvals for weight management, diabetes, sleep apnea, and cardiovascular risk reduction. Their potential role in cancer prevention remains under active investigation.

AI Disclaimer: This article was created with the assistance of AI tools and reviewed by a human editor.