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Once again, a large observational study suggests GLP-1 drugs confer an all-cause mortality benefit among patients with cancer.

The study, comparing GLP-1 use vs nonuse in more than 137,000 patients with breast cancer, showed a significant 4% increase in overall survival (OS) in those taking a GLP-1 drug.

Results were consistent after propensity score matching across confounders such as age, weight, comorbidities, cardiovascular history, and prior breast cancer therapies, first author Jasmine S. Sukumar, MD, told Medscape Medical News.

“The findings add to the portfolio of data in this space, which show an interesting signal of mortality benefit,” said Sukumar, who is an assistant professor of breast medical oncology at The University of Texas MD Anderson Cancer Center in Houston.

A co-author presented the findings in a poster at the American Society of Clinical Oncology (ASCO) 2026.

Sukumar and her colleagues used data for 137,493 patients with invasive breast cancer extracted from a commercial insurance claims database, including 7249 who received a GLP-1 for at least 3 months. Of those, 80% were using GLP-1s to treat type 2 diabetes.

The median duration of GLP-1 use was 2.1 years, and use increased over time, from 3.2% in 2014 to 5.2% in 2018 and 7.2% in 2023.

In the propensity score-matched cohort, including 7248 GLP-1 users and 7248 nonusers, 5-year OS was 95.8% vs 89.5%, respectively (adjusted hazard ratio, 0.41).

Multiple studies, including another presented at ASCO that looked at real-world data from more than 12,000 patients with any of seven cancer types associated with obesity or diabetes, have linked GLP-1 use to improved cancer incidence and outcomes, as well as to improved all-cause survival.

Most, however, have important limitations, and findings have been conflicting.

For example, in a separate recent study, Sukumar and her colleagues found that GLP-1 use among 1022 patients with breast cancer at MD Anderson was associated with weight loss and improved all-cause survival but not disease-free survival. Conversely, a recently published cohort study of more than 800,000 patients with breast cancer suggested a potential association between GLP-1 use and cancer-related outcomes.

Thus, the question of whether GLP-1 drugs have direct effects on cancer remains unanswered, Sukumar said.

The current findings further underscore the need for prospective randomized studies to clarify the biological mechanisms underlying the associations observed between GLP-1 use and mortality outcomes, including metabolic health implications and effects on tumor biology, the investigators said.

Sukumar reported having no disclosures.

Sharon Worcester, MA, is an award-winning medical journalist based in Birmingham, Alabama, writing for Medscape, MDedge, and other affiliate sites. She currently covers oncology, but she has also written on a variety of other medical specialties and healthcare topics. She can be reached at sworcester@mdedge.comor on X: @SW_MedReporter.