In the weeks around the 2026 annual meeting of the American Society of Clinical Oncology, my phone kept buzzing with alerts about GLP-1 drugs and cancer. The headlines were everywhere – from NPR and The Washington Post to Substack and heated exchanges on social media – all circling the same claim: Ozempic might lower the risk of cancer.
Behind those headlines is a real wave of studies, involving millions of patients. I’m a physician and clinical epidemiologist, and my team and I design and interpret these same kinds of studies that test what widely used drugs actually do.
The excitement around the idea that GLP-1 drugs can prevent cancer is running well ahead of the evidence. Not wrong, necessarily. Just not yet earned.
Cancer is among the many hardest issues to review, as a result of it’s not one illness however greater than 100. Breast most cancers, lung most cancers and blood cancers aren’t variations of the identical illness; every has its personal distinct biology and its personal mixture of genetic, environmental and behavioral dangers.
A single drug by no means will get one verdict on the way it impacts most cancers. It will get 100, elevating the chance of some, reducing it for others and leaving most untouched.
The early most cancers considerations
Earlier than the present buzz that GLP-1 medication might scale back most cancers threat, the fear ran in the other way: that they may increase most cancers threat.
Researchers have been initially involved about thyroid most cancers. Research in rodents discovered that Ozempic precipitated thyroid C cell tumors, which is why U.S. regulators added a black field warning in June 2026 to the drug that advises towards its use amongst these with a private or household historical past of associated circumstances.
However rodents aren’t folks. Human thyroid C cells are much less delicate to GLP-1 medication in comparison with rodent C cells as a result of they’ve far fewer GLP-1 receptors. Lengthy-term research in monkeys didn’t present the identical irregular thyroid cell development seen in rodents.
A 2025 evaluation of knowledge from 93 medical trials discovered no clear hyperlink between taking sure GLP-1 medication and thyroid most cancers. European regulators reached the identical conclusion in 2023 after reviewing accessible analysis on GLP-1s.
Pancreatic most cancers was one other concern. Right here, too, researchers discovered no constant elevated threat from taking GLP-1 medication in a 2025 evaluation of knowledge from 62 research.
The reassurance is actual however provisional. These medication are younger, and most cancers can take a long time to floor.
The most cancers story activates its head
GLP-1 medication, as soon as scrutinized for presumably inflicting most cancers, at the moment are being mentioned as medication that may forestall and even deal with most cancers.
A 2024 examine of greater than 1.6 million folks with Kind 2 diabetes discovered decrease charges of 10 out of 13 obesity-related cancers in folks handled with a GLP-1 drug in comparison with insulin.
A 2025 examine of about 87,000 adults discovered that general most cancers charges amongst those that began a GLP-1 drug have been roughly 17% decrease, with the clearest reductions in endometrial and ovarian cancers in addition to a kind of mind most cancers known as meningioma. The danger of kidney most cancers was 38% increased amongst sufferers taking GLP-1 medication, although bigger research are wanted to substantiate its significance.
A 2026 examine of greater than 110,000 ladies present process breast imaging discovered a roughly 30% decrease threat of breast most cancers amongst those that use GLP-1 medication in comparison with those that don’t.
Researchers are additionally learning how GLP-1 medication have an effect on a affected person’s possibilities of surviving most cancers. Amongst greater than 6,800 colon most cancers sufferers in a 2024 examine, round 16% of the 103 on a GLP-1 drug died inside 5 years in comparison with 37% of those that weren’t taking one. A examine offered on the 2026 American Society of Scientific Oncology reported a 34% decrease threat of dying throughout six most cancers sorts for these taking GLP-1 medication.
Why the proof is very easy to misinterpret
Whereas these findings are thrilling, research on the results of GLP-1 medication on most cancers threat have three options that make them particularly straightforward to misinterpret.
The primary is wholesome person bias. Individuals who begin a GLP-1 drug are usually more healthy and wealthier than those that don’t. An individual with weight problems who has insurance coverage, sees docs recurrently and might afford Ozempic is much extra prone to begin the drug than somebody with the identical peak and weight who lacks these benefits.
Wholesome person bias could be very tough to wash out of observational research, which evaluate folks as they’re handled in actual life fairly than assigning the drug at random. The very benefits that made it potential to obtain a GLP-1 prescription, not the drug itself, could also be what lowered a affected person’s most cancers threat.
The second is the selection of the comparability drug. To grasp the impact of a drug, it needs to be measured towards one thing else. What it’s measured towards will form the outcomes of the examine. The 2024 examine reported that sufferers taking GLP-1 medication noticed giant reductions in most cancers threat in comparison with these taking insulin. However evaluating sufferers on GLP-1 medication with sufferers taking the diabetes drug metformin confirmed no clear discount in most cancers threat.
Insulin is reserved for sufferers with extra superior diabetes, a situation that’s itself a threat issue for most cancers. In these research, sufferers on insulin begin out with the next threat of most cancers. Measured towards a gaggle at increased threat of growing most cancers, nearly something can look protecting. The obvious profit got here from the comparability drug, not the GLP-1 drug.
The third is timing. It isn’t a lot one other supply of bias as a clue that different biases could also be at work. Most cancers can take a long time to develop, but most GLP-1 research comply with folks for less than a handful of years. In some research, the obvious most cancers advantages of GLP-1 medication present nearly instantly. However prevention doesn’t work that shortly. A drug that actually lowered the chance of growing most cancers would present its impact regularly as fewer tumours floor over time, not inside the first few months of taking a drug.
When most cancers threat seems to drop nearly as quickly as a affected person begins remedy, the velocity isn’t a magical triumph of GLP-1 medication. Somewhat, for my part, it’s the inform: Individuals who begin these medication have been already at decrease most cancers threat, and the GLP-1 medication are getting credit score for that preexisting benefit.
Furthermore, nearly all of this analysis comes from a handful of high-income international locations, whilst uptake of those medication is rising globally and the burden of most cancers has disproportionately grown in lower-income international locations. The concept GLP-1s could scale back most cancers threat for a lot of the world is being inferred from information generated nearly totally in a couple of wealthy ones.
What do randomized trials present?
The cleanest means round these examine biases is randomized trials, which by design make comparability teams alike from the beginning.
Accessible medical trials inform a quieter story than the headlines. Two 2025 meta-analyses, which pool information from a number of research – one overlaying 50 trials and a second overlaying 48 – discovered little proof that GLP-1 medication both increase or decrease most cancers threat.
The findings of those meta-analyses are usually extra dependable than these of observational research as a result of their complete quantity of knowledge will increase their statistical energy. Regardless of their strengths, these analyses inherit the constraints of the trials they embody. Many of the trials in these 2025 research had a brief follow-up of a 12 months or two and recorded too few most cancers instances to settle the query.
Randomized medical trials designed to reply the query of whether or not GLP-1 medication have an effect on most cancers threat would want to enroll tens of 1000’s of individuals and comply with them for a few years. In need of that, the subsequent greatest proof will come from observational research designed to emulate randomized trials.
Till then, the concept that GLP-1 medication decrease most cancers threat is a speculation price testing however not a conclusion to behave on.
The underside line
Based mostly on the accessible proof, the clearest conclusion is the reassuring one: GLP-1 medication don’t seem to boost general most cancers threat. Nonetheless, extra formidable claims that GLP-1s actively forestall most cancers or enhance survival after prognosis stay unproven.
Suppose GLP-1s do impact most cancers threat. Researchers nonetheless wouldn’t know the place that impact comes from: weight reduction itself, broader enchancment in metabolic perform, or a extra direct impact on irritation, the immune system or tumors.
The surest factor I can say can also be the least satisfying: It’s nonetheless too early. These medication are far youthful than the cancers they’re being credited with stopping.
Ziyad Al-Aly, Scientific Epidemiologist, Washington College in St. Louis
The article was initially printed on The Dialog.
