Within the weeks across the 2026 annual assembly of the American Society of Medical Oncology, my telephone stored buzzing with alerts about GLP-1 medication and most cancers. The headlines had been in all places — from NPR and The Washington Publish to Substack and heated exchanges on social media — all circling the identical declare: Ozempic may decrease the chance of most cancers.
Behind these headlines is a actual wave of research, involving thousands and thousands of sufferers. I am a doctor and medical epidemiologist, and my group and I design and interpret these similar sorts of research that take a look at what broadly used medication truly do.
The thrill round the concept that GLP-1 medication can forestall most cancers is working effectively forward of the proof. Not incorrect, essentially. Simply not but earned.
Most cancers is among the many hardest issues to check, 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, decreasing it for others and leaving most untouched.
The early most cancers issues
Earlier than the present buzz that GLP-1 medication may scale back most cancers danger, the concern ran in the other way: that they could elevate most cancers danger.
Researchers had been initially involved about thyroid most cancers. Research in rodents discovered that Ozempic triggered thyroid C cell tumors, which is why U.S. regulators added a black field warning in June 2026 to the drug that advises in opposition to its use amongst these with a private or household historical past of associated circumstances.
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However rodents aren’t individuals. 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 information 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 out there analysis on GLP-1s.
Pancreatic most cancers was one other concern. Right here, too, researchers discovered no constant elevated danger from taking GLP-1 medication in a 2025 evaluation of information from 62 research.
The reassurance is actual however provisional. These medication are younger, and most cancers can take many years to floor.
The most cancers story activates its head
GLP-1 medication, as soon as scrutinized for probably inflicting most cancers, are actually being mentioned as medication that may forestall and even deal with most cancers.
A 2024 research of greater than 1.6 million individuals with Sort 2 diabetes discovered decrease charges of 10 out of 13 obesity-related cancers in individuals handled with a GLP-1 drug in comparison with insulin.
A 2025 research of about 87,000 adults discovered that total most cancers charges amongst those that began a GLP-1 drug had 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 chance of kidney most cancers was 38% greater amongst sufferers taking GLP-1 medication, although bigger research are wanted to substantiate its significance.
A 2026 research of greater than 110,000 ladies present process breast imaging discovered a roughly 30% decrease danger of breast most cancers amongst those that use GLP-1 medication in comparison with those that don’t.
Researchers are additionally finding out how GLP-1 medication have an effect on a affected person’s probabilities of surviving most cancers. Amongst greater than 6,800 colon most cancers sufferers in a 2024 research, 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 research introduced on the 2026 American Society of Medical Oncology reported a 34% decrease danger of loss of life throughout six most cancers varieties 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 danger have three options that make them particularly simple 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 top and weight who lacks these benefits.
Wholesome person bias may be very tough to wash out of observational research, which examine individuals as they’re handled in actual life reasonably than assigning the drug at random. The very benefits that made it doable to obtain a GLP-1 prescription, not the drug itself, could also be what lowered a affected person’s most cancers danger.
The second is the selection of the comparability drug. To grasp the impact of a drug, it must be measured in opposition to one thing else. What it is measured in opposition to will form the outcomes of the research. The 2024 research reported that sufferers taking GLP-1 medication noticed giant reductions in most cancers danger 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 danger.
Insulin is reserved for sufferers with extra superior diabetes, a situation that’s itself a danger issue for most cancers. In these research, sufferers on insulin begin out with the next danger of most cancers. Measured in opposition to a bunch at greater danger of creating most cancers, virtually something can look protecting. The obvious profit got here from the comparability drug, not the GLP-1 drug.
The third is timing. It’s not a lot one other supply of bias as a clue that different biases could also be at work. Most cancers can take many years to develop, but most GLP-1 research observe individuals for less than a handful of years. In some research, the obvious most cancers advantages of GLP-1 medication present virtually instantly. However prevention does not work that rapidly. A drug that actually lowered the chance of creating most cancers would present its impact step by step as fewer tumors floor over time, not inside the first few months of taking a drug.
When most cancers danger seems to drop virtually as quickly as a affected person begins remedy, the pace will not be a magical triumph of GLP-1 medication. Somewhat, for my part, it’s the inform: Individuals who begin these medication had been already at decrease most cancers danger, and the GLP-1 medication are getting credit score for that preexisting benefit.
Furthermore, virtually all of this analysis comes from a handful of high-income nations, whilst uptake of those medication is rising globally and the burden of most cancers has disproportionately grown in lower-income nations. The concept GLP-1s might scale back most cancers danger for a lot of the world is being inferred from information generated virtually solely in a couple of wealthy ones.
What do randomized trials present?
The cleanest approach round these research biases is randomized trials, which by design make comparability teams alike from the beginning.
Obtainable medical trials inform a quieter story than the headlines. Two 2025 meta-analyses, which pool information from a number of research — one protecting 50 trials and a second protecting 48 — discovered little proof that GLP-1 medication both elevate or decrease most cancers danger.
There are various GLP-1 manufacturers out there for shoppers.
(Picture credit score: Iuliia Burmistrova by way of Getty Photos)
The findings of those meta-analyses are typically extra dependable than these of observational research as a result of their complete quantity of information will increase their statistical energy. Regardless of their strengths, these analyses inherit the restrictions of the trials they embrace. A lot of the trials in these 2025 research had a brief follow-up of a 12 months or two and recorded too few most cancers circumstances 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 danger would wish to enroll tens of hundreds of individuals and observe them for a few years. In need of that, the following finest proof will come from observational research designed to emulate randomized trials.
Till then, the concept that GLP-1 medication decrease most cancers danger is a speculation price testing however not a conclusion to behave on.
The underside line
Primarily based on the out there proof, the clearest conclusion is the reassuring one: GLP-1 medication don’t seem to lift total most cancers danger. Nonetheless, extra bold claims that GLP-1s actively forestall most cancers or enhance survival after analysis stay unproven.
Suppose GLP-1s do affect most cancers danger. 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 is nonetheless too early. These medication are far youthful than the cancers they’re being credited with stopping.
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