Weight loss drugs such as Ozempic and Wegovy have become some of the most popular medicines recently. These drugs help millions of people manage obesity and type 2 diabetes. Now, researchers have discovered another possible benefit that could have a major impact. A new study found that women who take GLP-1 medications, such as Ozempic, Wegovy, Mounjaro, and Zepbound, may have a significantly lower risk of developing breast cancer. The findings of the study were presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and published in JCO Oncology Practice.
While the study does not prove that these medications directly prevent cancer, it adds to the evidence that GLP-1 drugs may do more than help people lose weight. Researchers believe that these medicines could become part of cancer prevention strategies, although more studies are needed.
What Did The Study Find?
The study was conducted by scientists at the University of Pennsylvania and involved more than 110,000 women between the ages of 45 and 80. Researchers examined health records to compare women who used GLP-1 medications with those who did not. The results showed that women taking these drugs were about 30% less likely to develop breast cancer than women who were not using them.
The reduced risk was present even after researchers accounted for factors such as age, race, ethnicity, body mass index (BMI), breast density, and diabetes status.
Elizabeth McDonald, MD, PhD, a professor of Radiology at the University of Pennsylvania Perelman School of Medicine and a practicing breast radiologist at Penn's Abramson Cancer Center, said, "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."
What Are GLP-1 Drugs?
GLP-1 medications mimic a naturally occurring hormone called glucagon-like peptide-1, which helps regulate appetite and blood sugar levels. These medicines were first developed to treat type 2 diabetes, however, they have now become widely known for their ability to support weight loss. Popular drugs include Ozempic and Wegovy, which contain semaglutide, as well as Mounjaro and Zepbound, which contain tirzepatide.
Why These Drugs May Lower The Risk?
Scientists believe there are several possible explanations. One obvious factor is weight loss itself. Excess body weight, particularly after menopause, is a known risk factor for breast cancer. By helping people lose weight and maintain a healthier body composition, GLP-1 medications may reduce some of the conditions that lead to cancer development.
However, weight loss may not be the only reason. Researchers also point to the anti-inflammatory effects of GLP-1 drugs. Chronic inflammation has been linked to the development of many cancers. These medications may help reduce inflammation and improve metabolic health, thereby, creating an environment that is not favourable for tumour growth.
Also, GLP-1 drugs can improve insulin sensitivity and lower insulin resistance. High insulin levels and metabolic disorders have been linked to higher risk of certain cancers, including breast cancer.
Why Researchers Are Being Cautious
Despite the encouraging results, experts stress that the study was observational. This means researchers looked at existing health records rather than conducting a controlled clinical trial. Observational studies can identify links between factors, but they cannot prove that one factor directly causes another. For example, women taking GLP-1 medications may have had other health habits or medical care patterns that impacted their cancer risk. Although the researchers adjusted for several risk factors, some unknown variables may still have played a role.
Due to these limitations, scientists say clinical trials are now needed to determine whether GLP-1 drugs directly reduce breast cancer risk and whether they could be recommended for cancer prevention.
McDonald said, "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."
Beyond diabetes and obesity treatment, researchers are exploring their potential benefits in heart disease, kidney disease, and now cancer prevention. Several studies presented at recent cancer conferences have also suggested that GLP-1 drugs may improve outcomes in other types of cancer.
"Ultimately, we want to find better options to prevent breast cancer. 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," added McDonald.
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