Weight-Loss Drugs May Lower Breast Cancer Risk and Improve Outcomes, New Studies Suggest

Weight-loss medications may offer benefits beyond obesity treatment, with new research indicating they could help reduce the risk of developing cancer and improve outcomes in patients already diagnosed with the disease.

Three studies presented at the 2026 annual meeting of the American Society of Clinical Oncology (ASCO) found promising links between GLP-1 receptor agonists and lower rates of cancer incidence, progression, and mortality.

In one study involving more than 110,000 women aged 45 to 80, researchers found that those taking GLP-1 medications were 30% less likely to develop breast cancer compared with women who did not use the drugs. Although the findings do not prove a direct cause-and-effect relationship, they add to growing evidence that these medications may have cancer-preventive potential.

“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 Dr. Elizabeth McDonald of the University of Pennsylvania’s Abramson Cancer Center.

A second study of 27,000 breast cancer patients found that adding GLP-1 medications to standard treatment was associated with a 30% reduction in the risk of death.

Meanwhile, a third analysis involving 12,000 patients with breast, lung, colorectal, or liver cancer showed that those taking weight-loss drugs were 38% to 50% less likely to develop metastatic stage IV disease.

Originally developed for type 2 diabetes, GLP-1 drugs mimic a naturally occurring hormone that regulates appetite and blood sugar levels. Their effectiveness in promoting weight loss has led to widespread use for obesity treatment.

Researchers believe the potential anticancer effects of these medications may extend beyond weight reduction. In addition to helping patients maintain a healthy body weight—a known factor in reducing breast cancer risk—GLP-1 drugs also appear to reduce chronic inflammation and influence biological pathways involved in tumor growth.

Experts caution that more research is needed to determine exactly how these drugs affect cancer risk and outcomes. However, growing interest in the field is prompting calls for large prospective studies to evaluate their role in cancer prevention and treatment.

Some oncologists also report that patients taking GLP-1 medications often experience improved well-being and may better tolerate certain cancer therapies, further increasing interest in their potential use in oncology.