17% Lower Cancer Risk: The JAMA Oncology Study Explained

A study of 86,000+ adults found that GLP-1 medication users had 17% fewer new cancer diagnoses. The strongest signals were for endometrial cancer, ovarian cancer, and meningioma.

In August 2025, JAMA Oncology published one of the largest studies to date examining the relationship between GLP-1 medications and cancer risk. The results added significant weight to the hypothesis that these drugs may offer protective effects against certain cancers — while also raising important questions that still need answers. JAMA Oncology

The Study at a Glance

Researchers from the University of Florida and Indiana University analyzed electronic health records from the OneFlorida+ health network, which covers over 86,000 adults with obesity or overweight tracked between 2014 and 2024. They compared cancer diagnoses between GLP-1 receptor agonist users and matched non-users.

The primary finding: adults taking GLP-1 medications had a 17% lower risk of being diagnosed with one of the 14 obesity-related cancers tracked by the study.

Where the Signal Was Strongest

The overall 17% risk reduction was driven by particularly strong signals in three cancer types:

A separate ASCO presentation analyzing 170,000+ patients found similar patterns, with colorectal cancer also showing a notable risk reduction in GLP-1 users. ASCO

The Nuances

Science demands honesty about limitations, and this study has them. It was observational — meaning it tracked existing patterns rather than randomly assigning treatment. People who take GLP-1 medications may differ from non-users in ways that independently affect cancer risk (better healthcare access, more health-conscious behaviors, different screening rates).

There was also one concerning signal: a potentially increased risk of kidney cancer in GLP-1 users. The researchers emphasized this finding needs longer-term follow-up to understand whether it's a genuine effect or statistical noise.

A separate analysis of 48 randomized controlled trials (Annals of Internal Medicine, December 2025) found "little or no effect" on obesity-related cancer risk, though the studies were primarily designed for other endpoints and may not have followed patients long enough to detect cancer differences.

Reconciling the Evidence

How do we make sense of seemingly conflicting evidence? The key may be timing. Cancer takes years or decades to develop. The randomized trials followed patients for 1-4 years — possibly not long enough to capture cancer prevention effects. The observational studies, which tracked patients over longer periods, show more promising signals.

Additionally, GLP-1 medications may affect cancer outcomes through mechanisms that wouldn't show up in short-term trials: reduced chronic inflammation, improved immune function, lower insulin and IGF-1 levels, and reduced obesity-driven hormonal imbalances that promote certain cancers.

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