Women taking popular GLP-1 weight loss drugs like Ozempic and Wegovy had a 30 percent reduced risk of developing breast cancer compared to those not on the medications, according to a new study from the University of Pennsylvania Perelman School of Medicine.
Study Details and Findings
The findings build on years of previous research linking GLP-1 use to improved outcomes for multiple types of cancer, although past studies have shown little effect on reducing obesity-related cancers like breast cancer. The study examined health records of over 110,000 overweight American women aged 45 to 80 over three years from 2022 to 2025, with 15,264 initially taking the drugs. It did not account for specific GLP-1 types, genetic history, or cancer stage at diagnosis.
Breast cancer accounts for nearly a third of all cancer cases among women in the U.S., and the American Cancer Society estimates about 42,140 women will die from it this year. The researchers say their work supports further investigation into the medications' potential for cancer prevention.
Expert Commentary
Dr. Elizabeth McDonald, a radiologist and professor at the school, stated: "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."
She added: "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."
Potential Mechanisms
GLP-1 drugs work by mimicking the hormone glucagon-like peptide-1, which regulates blood sugar and appetite, helping users lose significant weight. Obesity is a known risk factor for breast cancer and triggers harmful inflammation that may affect tumor growth. The drugs address both weight and inflammation, though it remains unclear if these effects directly explain the reduced cancer risk.
Future Research
Future studies will address genetic factors and cancer stages, and McDonald's team is planning a clinical trial to assess whether the drugs can lower breast cancer rates in high-risk women and those with a history of the disease. "Ultimately, we want to find better options to prevent breast cancer," 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."
