Ozempic and similar weight-loss drugs were linked to a striking 30% reduction in breast cancer risk in a study of more than 110,000 women.
Popular weight-loss and diabetes medications such as Ozempic, Wegovy, Mounjaro, and Zepbound may offer an unexpected benefit beyond helping people lose weight. A large new study found that women taking these drugs were significantly less likely to develop breast cancer than women who were not using them.
The research, presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting and published in JCO Oncology Practice, analyzed health records from more than 110,000 women. Researchers found that women taking GLP-1 medications, a class of drugs that includes semaglutide (the active ingredient in Ozempic and Wegovy) and similar treatments, had about a 30% lower risk of developing breast cancer.
"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," said 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.
Ozempic and Similar Drugs Draw Interest From Cancer Researchers
GLP-1 medications mimic a naturally occurring hormone called glucagon-like peptide-1, which helps regulate blood sugar and appetite. Drugs in this category were originally developed for type 2 diabetes but have become household names because of their effectiveness for weight loss.
Ozempic and Wegovy contain semaglutide, while Mounjaro and Zepbound use a related medication called tirzepatide. Together, these drugs are now used by millions of Americans.
Researchers have increasingly become interested in whether these medications might also affect cancer risk. Several recent observational studies have linked GLP-1 drugs to lower rates of certain cancers or improved outcomes among cancer survivors. However, researchers stress that prospective clinical trials, considered the gold standard of medical research, are still needed.
McDonald and her colleagues are currently working to launch a multisite clinical trial to determine whether GLP-1 medications can help prevent breast cancer in women at elevated risk, including some with a history of the disease.
"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," McDonald said.
Study of More Than 110,000 Women Finds Lower Breast Cancer Rates
The researchers examined electronic health records from 111,646 women between the ages of 45 and 80 who had a body mass index (BMI) of 25 or higher and underwent breast imaging through Penn Medicine between January 2022 and June 2025.
Among these women, 15,264 (13.7 percent) had documented prescriptions for GLP-1 medications, while 96,382 (86.3 percent) had no documented exposure to the drugs.
The team looked for new breast cancer diagnoses in two groups. The first included the entire study population. The second included a smaller matched cohort of 30,528 women. In that analysis, each woman taking a GLP-1 drug was paired with a nonuser who shared similar characteristics, including age, race, ethnicity, BMI, breast density, and diabetes status.
The findings were consistent across both groups. In the full study population, GLP-1 users had 35.1 percent lower odds of developing breast cancer. In the matched analysis, the reduction was 30.5 percent.
The study did not account for the specific type of GLP-1 medication used, how long participants took the drugs, inherited genetic risk factors, or the stage and type of cancer diagnosed. Researchers plan additional analyses to explore some of these questions.
Why Might Ozempic and Other GLP-1 Drugs Affect Cancer Risk?
Maintaining a healthy weight has long been considered an important part of breast cancer prevention because excess body weight, especially after menopause, is a well-established risk factor.
Because Ozempic, Wegovy, Mounjaro, and Zepbound can produce substantial weight loss, some of the observed benefit may be linked to improved weight management. However, researchers believe other biological effects could also be involved.
Scientists have long suspected that chronic low-grade inflammation contributes to cancer development. GLP-1 medications reduce inflammation through multiple pathways and also influence metabolism and epigenetic processes that help regulate gene activity. Researchers currently believe this combination of effects may help slow or prevent tumor formation.
Searching for Better Ways to Prevent Breast Cancer
Current options for reducing breast cancer risk remain limited.
Beyond regular screening with mammography or MRI, some people with inherited genetic mutations that greatly increase breast cancer risk choose preventive surgery, including prophylactic mastectomy.
Tamoxifen can substantially reduce breast cancer incidence in high-risk women, but concerns about side effects have limited its use among many eligible patients.
Because GLP-1 medications such as Ozempic, Wegovy, Mounjaro, and Zepbound are already widely prescribed, researchers see them as a potentially promising avenue for future cancer prevention research.
"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."
Reference: "GLP-1 Agonists Are Associated With a Significant Reduction in Breast Cancer Incidence in Women" by Elizabeth S. McDonald, Laura B. Gillis, Peter Gabriel, Kham Xapakdy, Anthony Young, Abigail Doucette, Mitchell D. Schnall, John B. Buse and Etta D. Pisano, 2 June 2026, JCO Oncology Practice.
DOI: 10.1200/OP-26-00485
The study was supported by the American College of Radiology Center for Research and Innovation, the Pennsylvania Breast Cancer Coalition, and the Abramson Cancer Center.
News – Curated by Amanda Scott, Alias Group Creative
Follow her on Bluesky
Where do nanoparticles go once they enter the body?
New international best practice guidance, co-written at ANSTO, sets out how to measure where nanoparticles like titanium dioxide end up in the body and how long they remain. The guidance has been shared by [...]
Long-Acting HIV Shots Could Solve a Major Treatment Challenge for Young People
A major African trial suggests that changing how HIV treatment is delivered could significantly improve viral suppression in adolescents. Young people with HIV were more likely to keep the virus suppressed when they received [...]
WHO Factsheets – The top 10 causes of death
In 2023, the 10 leading causes of death accounted for 33 million deaths, or 54% of the total 61 million deaths worldwide. The top global causes of death, in order of total number of lives lost, [...]
Aging Cells May Be Hiding From the Immune System – Scientists Think They Know How
Your immune system is supposed to clear out damaged cells. Researchers may have found how some of them hide and linger as the body ages. Researchers led by Cedars-Sinai Health Sciences University have identified [...]
Your Voice May Reveal How Fast Your Brain Is Aging
Researchers have developed a machine-learning “speech clock” that estimates age from subtle patterns in how people speak and what they say. It is possible that people’s voices may contain certain signals of aging that [...]
Optogenetics Pioneers Win 2026 Nobel Prize in Physiology or Medicine
The 2026 Nobel Prize in Physiology or Medicine has been awarded to Peter Hegemann, Georg Nagel, and Karl Deisseroth for the development of optogenetics, a revolutionary technology that uses light to control individual neurons [...]
Molecular Manufacturing: The Future of Nanomedicine – From NanoappsMedical Inc.
This book explores the revolutionary potential of atomically precise manufacturing technologies to transform global healthcare, as well as practically every other sector across society. This forward-thinking volume examines how envisaged Factory@Home systems might enable the cost-effective [...]
What is ‘American Covid’ and how bad is it?
Cases of so-called ‘American Covid’ are on the rise in the UK. The strain is officially called XFG, or ‘Stratus’, and is the most common variant in North America, hence the name. It might soon [...]
Researcher at Russian plague laboratory dies of ‘unknown’ infection
Russian authorities have imposed "anti-epidemic measures" after a laboratory worker at an institute in Siberia dedicated to studying the plague and other infectious diseases died of a mysterious illness. The researcher, a 28-year-old female [...]
GHCE Concept
From the preface of the book Global Health Care Equivalency in the Age of Nanotechnology, Nanomedicine and Artificial Intelligence, Edited by Frank Boehm: Since the publication of my first book (Nanomedical Device and Systems [...]
A Surprising Brain Signal Could Explain Why Eating Less Protein Extends Lifespan
A new paper suggests that limiting protein intake triggers a coordinated response throughout the body that may help explain how protein restriction affects healthy aging. Animals respond to protein restriction, or reduced protein in [...]
Back and shoulder surgery is often worse than useless
Millions of operations should be scrapped SIX IN TEN Britons have surgery at some point. So do lots of Americans, at a cost of perhaps $500bn a year, a third of all spending on [...]
Cocaine plays with mind, hijacks brain circuit, drives increasingly rigid and repetitive behavior
Researchers have found that cocaine hijacks brain circuit, which to drive increasingly rigid and repetitive behavior. The brain circuit that normally participates in selecting natural mouth and face movements, but which becomes disproportionately engaged [...]
Injectable nanodevices could provide effective treatment for drug-resistant glioblastoma
The brain cancer glioblastoma is one of the most aggressive and treatment-resistant cancers known to medicine, carrying a median survival of just 12-15 months, even with the best available care. Now, researchers at the [...]
New Treatment Cuts “Bad” Cholesterol in Half for a Full Year
A single infusion of an experimental CRISPR-Cas9 therapy was reported to safely lower LDL cholesterol by 52.5% and triglycerides by 47.8%, as measured 12 months after treatment. What if one infusion could keep cholesterol [...]
Too Much RNA Can Drain a Cell’s Energy, Scientists Discover
A virus may cripple a cell’s power supply simply by producing too much of a molecule the cell needs to survive. New research from the Texas A&M College of Veterinary Medicine and Biomedical Sciences [...]
