Can Ozempic Prevent Cancer? Why the Headlines Are Misleading

GLP-1 receptor agonists, including drugs like Ozempic, do not appear to increase overall cancer risk, though evidence that they actively prevent or treat cancer remains unproven, according to a clinical epidemiologist and physician writing for The Conversation. While some observational studies suggest lower cancer rates among users, experts warn that these findings are often skewed by healthy user bias and the choice of comparison drugs.

The debate over GLP-1 drugs and oncology intensified around the 2026 annual meeting of the American Society of Clinical Oncology. Public discussion shifted from concerns that the drugs might cause tumors to claims that they could serve as cancer preventatives.

Early Concerns Over Thyroid and Pancreatic Cancers

Initial medical scrutiny focused on whether GLP-1 drugs increased the risk of specific malignancies. In June 2026, U.S. regulators added a black box warning to one such drug, advising against its use for patients with a personal or family history of thyroid C cell tumors after rodent studies showed the drugs caused such tumors.

Human biology differs from rodent biology in this regard. Human thyroid C cells have fewer GLP-1 receptors, making them less sensitive to the drugs. Long-term studies in monkeys did not show the abnormal thyroid cell growth seen in rodents, according to the report in The Conversation.

Further data has mitigated these early fears. A 2025 analysis of 93 clinical trials found no clear link between GLP-1 drugs and thyroid cancer. European regulators reached the same conclusion in 2023. Similarly, a 2025 analysis of 62 studies found no consistent increased risk of pancreatic cancer associated with the drugs.

Observational Studies Suggesting Cancer Reduction

Recent observational data has produced results that appear to show a protective effect against various cancers. These studies track patients in real-world settings rather than in controlled trials.

• Obesity-Related Cancers: A 2024 study of 1.6 million people with Type 2 diabetes found lower rates of 10 out of 13 obesity-related cancers in GLP-1 users compared to those using insulin.
• General Cancer Rates: A 2025 study of 87,000 adults reported that overall cancer rates were roughly 17% lower for those starting a GLP-1 drug, with the most significant reductions in ovarian, endometrial, and meningioma (a brain cancer).
• Breast Cancer: A 2026 study of 110,000 women undergoing breast imaging found a roughly 30% lower risk of breast cancer among GLP-1 users.
• Survival Rates: A 2024 study of 6,800 colon cancer patients found that 16% of the 103 patients on a GLP-1 drug died within five years, compared to 37% of those not taking the drug.

A study presented at the 2026 American Society of Clinical Oncology further claimed a 34% lower risk of death across six cancer types for patients taking GLP-1 drugs.

Why Experts Caution Against Misreading the Data

Clinical epidemiologists warn that these observational findings are easy to misinterpret due to three primary biases: healthy user bias, comparison drug selection, and timing.

Healthy user bias occurs because patients who can afford and access GLP-1 drugs often have better insurance and more frequent medical care than those who do not. These socioeconomic advantages, rather than the medication, may be the actual drivers of lower cancer risk.

The choice of comparison drug also distorts results. The 2024 study showing reduced cancer risk compared GLP-1 users to patients on insulin. Because insulin is typically reserved for patients with advanced diabetes—a condition that is itself a cancer risk factor—the insulin group started with a higher baseline risk. When GLP-1 drugs were compared to the diabetes drug metformin, no clear reduction in cancer risk was found.

Timing provides another red flag. Cancer typically takes decades to develop, yet some GLP-1 studies show benefits almost immediately after treatment begins. The physician and epidemiologist writing for The Conversation notes that true prevention does not work that quickly, suggesting that users may have already been at a lower risk before starting the drug.

What Randomized Trials Reveal

Randomized clinical trials, which eliminate many of the biases found in observational studies, offer a more conservative outlook. Two 2025 meta-analyses—one covering 50 trials and another covering 48—found little evidence that GLP-1 drugs either raise or lower cancer risk.

These trials have limitations. Most had a follow-up period of only one or two years and recorded too few cancer cases to reach a definitive conclusion. To settle the question, researchers would need to follow tens of thousands of people over many years.

Currently, it remains unknown if any observed benefits stem from the drug’s direct effect on tumors and inflammation, or if they are simply the result of weight loss and improved metabolic function.