CHICAGO — Researchers reported new findings on Monday that weight-loss medications in the GLP-1 drug class were associated with a lower risk of some cancers, adding to growing research on the possible health effects of medicines originally developed for diabetes and obesity treatment. The findings, presented at the 2026 annual meeting of the American Society of Clinical Oncology (ASCO), examined links between GLP-1 medications and cancer outcomes, but researchers said the results do not prove the drugs prevent cancer.
The study from researchers at the University of Pennsylvania analyzed health records from more than 100,000 women and found that those who used GLP-1 medications, including drugs such as semaglutide-based treatments, had a lower observed likelihood of developing breast cancer compared with those who did not use the medicines. The researchers reported that the difference was about 30%, while emphasizing that the study was observational and cannot establish that the medications directly caused the reduction.
“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,” Elizabeth McDonald, a professor at the University of Pennsylvania Perelman School of Medicine, said in comments reported by the university.
GLP-1 drugs, including medicines used for weight management and type 2 diabetes, work by affecting hormones involved in appetite and blood sugar regulation. Researchers have been studying whether their effects on body weight, metabolism and related biological processes may also influence cancer risk. Previous research has also examined possible associations between GLP-1 medications and several obesity-related cancers, though scientists have said further studies are needed.
Experts cautioned that the new findings should not be interpreted as proof that the drugs can be prescribed to prevent cancer. Cancer researchers have noted that differences between people who take GLP-1 medications and those who do not, including weight changes and other health factors, may influence results from observational studies.
The research comes as use of GLP-1 medications has expanded globally for obesity and diabetes care. The drugs have been studied for a range of potential health effects beyond weight loss, but regulatory approvals and medical guidance remain focused on their established uses. Details about whether the medications could play a role in cancer prevention remain under investigation, researchers said.
Further clinical research is expected to examine whether the observed relationship between GLP-1 drug use and lower cancer risk continues under controlled study conditions. Researchers said additional evidence will be needed before any conclusions are reached about possible cancer-prevention benefits.
