Women on weight-loss medication may have a lower risk of developing breast cancer, according to a new study.
Women who take GLP-1 medications, such as Ozempic or Mounjaro, are less likely to develop breast cancer, a new study has found.
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The findings, presented at the 2026 American Society of Clinical Oncology (ASCO) annual meeting, come from an analysis of more than 110,000 women aged between 45 and 80.
“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,” said Elizabeth McDonald, professor of radiology in the University of Pennsylvania Perelman School of Medicine and breast radiologist.
The study found that women who had used GLP-1 medications were around 30% less likely to develop breast cancer, independent of age, race, ethnicity, BMI, breast density and diabetes.
“There is extensive evidence that weight influences breast cancer risk and that lifestyle modification, including weight loss, can reduce this risk,” the authors wrote.
The researchers noted that it is important to consider glucagon-like peptide-1 receptor agonists (GLP-1 agonists) in the broader context of weight interventions for cancer risk reduction.
These medications promote weight loss and improve markers of metabolic health. They work by mimicking natural hormones produced in the gut after eating, signaling the body to release more insulin, reduce appetite and keep blood sugar levels low.
The authors stressed that increasing evidence suggests that GLP-1 agonists may also offer benefits beyond weight loss, including reductions in systemic inflammation — a finding that is driving increased interest in these compounds for their potential cancer-preventative effects.
Breast cancer is one of the most common malignant tumors in women worldwide, and inflammation plays an important role in the occurrence and development of breast cancer.
It is the body’s immune response, but when it is long-lasting or chronic, it can create conditions that may help cancer cells grow, survive or spread more easily.
“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,” McDonald said.
The study was restricted to women with overweight and obesity, meaning the findings may not necessarily apply to women with other weights.
The authors also flag that women taking GLP-1 drugs tend to have more frequent medical check-ups, which could lead to higher cancer detection rates.
The researchers said the result warranted further research, with ambitious stretching beyond cancer.
“We propose advancing to a randomised trial to evaluate a trifecta of prevention: cancer, heart disease, and the metabolic changes and symptomatology associated with menopause,” they wrote.
Other studies presented at ASCO this year point in a similar direction. A separate Italian study found that women with advanced, hormone receptor-positive breast cancer — the most common type of breast cancer — who took GLP-1 drugs lived on average nearly 19 months longer than those who did not.
