GLP-1 Cancer Risk: What the Biggest Studies Show (2026)

Does taking a GLP-1 drug like Ozempic, Wegovy, Mounjaro or Zepbound raise or lower your cancer risk? The biggest studies so far link GLP-1 drugs to a lower risk of obesity-related cancers, not a higher one. In a 2025 study of about 920,000 people with type 2 diabetes, GLP-1 users had 13% lower risk than people on other diabetes drugs. Two caveats matter. These studies show a link, not proof, and two of them saw a possible rise in kidney cancer. The thyroid warning on the label comes from rodent studies.

This guide walks through each big study, cancer by cancer, in plain English.

Why researchers study GLP-1 and cancer risk

Extra body fat is linked to at least 13 kinds of cancer, according to the National Cancer Institute. Fat tissue raises insulin, inflammation and some hormones, and all three can help cancer cells grow. So if a drug helps people lose a lot of weight, it is fair to ask if cancer rates drop too.

There is also the opposite worry. GLP-1 drugs act on cells in the gut, pancreas and thyroid. Early animal studies found thyroid tumors in rodents, which is why every semaglutide and tirzepatide label carries a boxed warning. Both questions have been studied in very large groups of patients.

GLP-1 cancer studies at a glance

A hazard ratio (HR) below 1 means lower risk in GLP-1 users. Above 1 means higher risk. An HR of 0.87 means about 13% lower.

Do GLP-1 drugs reduce cancer risk?

The data point in that direction, but nobody can say yes for sure yet.

The 2025 study in the Journal of the National Cancer Institute used US insurance records from 2016 to 2021. It looked at 13 obesity-related cancers. GLP-1 users had 7.5 new cancers per 1,000 person-years, compared with 8.1 for people on other diabetes drugs. The gap held against every drug class: metformin (HR 0.90), DPP-4 inhibitors (0.88), sulfonylureas (0.81), SGLT2 inhibitors (0.73) and insulin (0.70). The drop was larger in people with more severe obesity. In people who were only overweight, there was no clear difference.

The 2025 JAMA Oncology study is the one most relevant to weight loss, since it included adults with obesity, not only diabetes. Using Florida health records from 2014 to 2024, it matched 43,317 GLP-1 users with 43,315 similar non-users. Cancer rates were 13.6 vs 16.4 per 1,000 person-years. The clearest drops were in:

• Endometrial cancer: 25% lower (HR 0.75)
• Ovarian cancer: 47% lower (HR 0.53)
• Meningioma, a usually benign brain tumor: 31% lower (HR 0.69)

Why "linked to" is not the same as "prevents"

All of these are observational studies. Researchers looked back at health records. They did not randomly assign people to a drug, as a clinical trial does.

People who get a GLP-1 prescription may differ from people who do not. They may see doctors more often, have better insurance or have healthier habits. The studies try to adjust for this, but they cannot remove it fully. Also, most people were followed for only a few years, while many cancers take a decade or more to develop.

So the honest summary is: promising, consistent, not proven. A drug label will not say "lowers cancer risk" until randomized trials show it.

GLP-1 and kidney cancer: the signal to watch

This is the one result that went the other way.

• In the 2024 JAMA Network Open study, GLP-1 users had higher kidney cancer risk than metformin users (HR 1.54).
• In the 2025 JAMA Oncology study, kidney cancer risk was 38% higher in GLP-1 users (HR 1.38), but the range of possible values crossed 1.0, so the authors called it "marginally nonsignificant."
• In the same 2024 study, kidney cancer was lower in GLP-1 users when compared with insulin users.

Mixed results like this often mean the comparison group matters a lot. The JAMA Oncology authors said longer follow-up is needed. If you have a history of kidney cancer, tell your prescriber.

GLP-1 thyroid cancer risk

The boxed warning on Ozempic, Wegovy, Mounjaro and Zepbound says these drugs caused thyroid C-cell tumors in rodents, and that it is unknown whether they do this in humans. The labels say not to use them if you or a family member has had medullary thyroid cancer (MTC), or if you have Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).

In humans, the large 2024 BMJ study from Scandinavia found no clear rise in thyroid cancer. In October 2023, the European Medicines Agency's safety committee reviewed the evidence and concluded it does not support a causal link between GLP-1 drugs and thyroid cancer. Our GLP-1 thyroid warning guide explains the rodent data and the symptoms to report, such as a lump in the neck or trouble swallowing.

GLP-1 and pancreatic cancer

This question came up early, because GLP-1 drugs act on the pancreas. In 2014, the FDA and the European Medicines Agency published a joint review in the New England Journal of Medicine. They said the data did not support a causal link with pancreatic cancer, and they kept monitoring it. Pancreatitis, an inflamed pancreas, is a real but rare risk listed on the labels. Read more in GLP-1 and pancreatitis.

GLP-1 and breast cancer

Breast cancer after menopause is on the obesity-related list. In the 2024 JAMA Network Open study, GLP-1 users did not have a clear drop in postmenopausal breast cancer compared with insulin users. The other studies did not single it out as a clear win either.

If you are a breast cancer survivor, the choice of GLP-1, and whether to use one at all, belongs to your oncologist and prescriber together. Some cancer treatments affect weight, appetite and bone, and those matter here.

Where muscle fits in

Weight loss is the likely reason GLP-1 drugs may lower cancer risk. But fast weight loss also takes some muscle with it. In the STEP 1 trial's body scan group, lean mass made up about 40% of the weight lost on semaglutide. Muscle helps you stay strong, keep your blood sugar steady and recover if you ever face surgery or treatment.

Sharpy gives you one protein target sized for your body, one 20-minute strength workout and one Shape Score a day, so you can see if you are losing fat and keeping muscle. Our long term side effects guide covers the other risks to know.

What to tell your doctor before starting a GLP-1

Bring this list to your appointment:

1. Any personal or family history of medullary thyroid cancer or MEN 2.
2. Any history of pancreatitis or pancreatic cancer.
3. Any current or past cancer, including kidney or breast cancer, and the treatments you had.
4. Any lump in your neck, trouble swallowing or a hoarse voice that will not go away.
5. All the medicines and supplements you take.

Keep up with the cancer screenings your doctor recommends for your age. A GLP-1 is not a reason to skip them. If you are choosing between drugs, our semaglutide vs tirzepatide guide compares the two most common options.

The bottom line

The biggest studies link GLP-1 drugs to fewer obesity-related cancers, especially endometrial and ovarian cancer, and the effect looks stronger in people with more weight to lose. The thyroid warning comes from rodents, and large human studies have not shown a clear rise. Kidney cancer is the one signal researchers are still checking. None of this is proof yet, so make the decision with your doctor. While you are on the drug, protect your muscle, and Sharpy turns that into one simple plan each day.

Sources

• Mao et al., GLP-1 receptor agonist and obesity-related cancer in overweight or obese patients with type 2 diabetes, J Natl Cancer Inst 2025
• Dai et al., GLP-1 Receptor Agonists and Cancer Risk in Adults With Obesity, JAMA Oncology 2025
• Wang et al., GLP-1 Receptor Agonists and 13 Obesity-Associated Cancers in Patients With Type 2 Diabetes, JAMA Network Open 2024 (Healio summary)
• Pasternak et al., GLP-1 receptor agonist use and risk of thyroid cancer, BMJ 2024
• EMA PRAC meeting highlights, October 2023 (thyroid cancer)
• Egan et al., Pancreatic Safety of Incretin-Based Drugs: FDA and EMA Assessment, NEJM 2014
• National Cancer Institute, Obesity and Cancer
• Wegovy prescribing information (DailyMed)