Patients taking GLP-1 receptor agonists after a cancer diagnosis were less likely to see their disease spread to the rest of the body, according to real-world data on 12,112 people presented at the 2026 American Society of Clinical Oncology Annual Meeting in Chicago.
The signal appeared in four obesity-linked cancers: non-small cell lung cancer, breast cancer, colorectal cancer, and hepatocellular (liver) carcinoma.
Researchers propose that GLP-1 drugs, which include semaglutide (the active ingredient in Novo Nordisk's Ozempic and Wegovy) and tirzepatide (Eli Lilly's Mounjaro and Zepbound), may act on cancer through weight loss, reduced chronic inflammation, and a direct effect on tumor tissue that carries the GLP-1 receptor.
A separate, larger study published in June 2026 in Annals of Oncology found that among more than 229,000 obese, non-diabetic US adults, starting a GLP-1 drug was associated with a 41% lower overall cancer risk compared with weight management through diet and exercise alone.
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How much cancer spread the drugs blocked
The ASCO analysis pulled patient records from the TriNetX global health network. It matched people with stage I to III cancer who began a GLP-1 drug after diagnosis against a similar group who started a gliptin, an older diabetes pill.
Metastatic progression, meaning the point at which the cancer spread beyond the original site to distant parts of the body, was consistently lower in the GLP-1 group. For non-small cell lung cancer, 10% progressed on GLP-1 drugs versus 22% on gliptins. In breast cancer, the split was 10% versus 20%. Colorectal cancer showed 13% versus 22%, and liver cancer 19% versus 28%.
Across the four cancer types, risk reductions ranged from 31% to 50%, with tumors that expressed higher levels of the GLP-1 receptor also linked to better overall survival.
Why researchers think it works
Obesity is one of the largest modifiable drivers of cancer, and health authorities count it among the leading preventable causes. Excess body weight fuels chronic inflammation, insulin resistance and hormonal shifts that can help tumors grow and spread.
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Weight loss from GLP-1 drugs cools that biology. But the researchers behind the Annals of Oncology paper argue the effect looks bigger than weight loss alone would predict, pointing to GLP-1 receptors that sit directly on tumor cells and to the drugs' anti-inflammatory activity as likely additional mechanisms.
Mark David Orland, MD, of the Taussig Cancer Institute at Cleveland Clinic, said the ASCO findings show that GLP-1 use "was associated with a meaningful reduction in cancer progression across 4 solid tumor types," adding that the results provide early evidence to justify further study.
A strong signal, not proof
Both studies are observational. That means they can show a link but cannot prove that GLP-1 drugs caused the drop in cancer spread or new cases. Patients who choose GLP-1 drugs may differ from those who do not in ways the analyses cannot fully control for.
Marcin Chwistek, MD, of Fox Chase Cancer Center, said the size and consistency of the ASCO data justify moving to randomized trials, which are now needed to confirm whether GLP-1 drugs belong in cancer care beyond their approved uses in diabetes and obesity.
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For now, the drugs remain approved for type 2 diabetes and chronic weight management. Patients being treated for cancer who take a GLP-1 drug, or who are considering one, should discuss the decision with their oncology team.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.