GLP-1 drugs including semaglutide show no rise in obesity-related cancers across 48 trials

A meta-analysis of 48 randomized controlled trials found that adults taking GLP-1 medications had no higher odds of a dozen cancer-related outcomes than adults taking placebo, according to findings published Dec. 9, 2025, in Annals of Internal Medicine ^[1].

The analysis pooled 94,245 participants. Twenty-six of the trials enrolled people with type 2 diabetes, 18 enrolled people with overweight or obesity, and four enrolled people with both ^[1]. Median follow-up was 70 weeks ^[1]. Semaglutide (Ozempic, Wegovy) was the drug tested in 42 percent of the trials and liraglutide (Saxenda, Victoza) in 21 percent ^[1]. The review included only trials of FDA-approved drugs that reported at least one cancer outcome, and it covered GLP-1 drugs and dual agonists, including tirzepatide (Mounjaro, Zepbound) ^[1].

People taking GLP-1s showed no difference in the odds of thyroid cancer, pancreatic cancer, breast cancer, kidney cancer, colorectal cancer, esophageal cancer, liver cancer, gallbladder cancer, ovarian cancer, endometrial cancer, multiple myeloma or meningioma compared with those taking placebo ^[1]. Because the estimates were imprecise, the researchers rated the certainty of evidence as moderate for thyroid, pancreatic, breast and kidney cancer and low for the other cancers ^[1].

The results held across several checks. Subgroup analyses that separated trials by duration, by whether they enrolled people with type 2 diabetes or obesity, and by whether they tested GLP-1s or dual agonists produced consistent findings ^[1]. Results also did not change when the researchers excluded trials judged to have a moderate or high risk of bias, or when they left out trials of drugs other than semaglutide or tirzepatide ^[1].

"Clinically, these findings support the overall safety of GLP-1s with regard to cancer, which is important given the rapid growth in these drugs use for diabetes, obesity and cardiometabolic disease," said Cho-Han Chiang, MD, MMSc, a hematology/oncology fellow at Northwell Health Cancer Institute ^[1]. "There were previously concerns regarding thyroid cancer and pancreatic cancer with the use of GLP-1s, but our study showed that GLP-1s probably do not increase the risk of thyroid, pancreatic and other cancers" ^[1].

Chiang said the results differ from earlier observational studies that found a lower cancer risk among adults using GLP-1s ^[1]. "The discrepancy likely stems from the fact that these are two different types of study design (randomized controlled trials vs. observational, nonrandomized data) and also differences in follow-up time," he said ^[1].

Why it matters for patients

Cancer risk is one of the questions adults weigh when they consider or continue GLP-1 treatment, and thyroid and pancreatic cancer had both been raised as concerns in earlier data ^[1]. This analysis draws on randomized trials rather than insurance-claims or registry data, and it found no increased odds across the 12 outcomes it examined ^[1].

Two limits are worth knowing. Median follow-up was about 70 weeks, roughly 16 months, which is short for cancers that can take years to develop, and Chiang said the trials' shorter follow-up makes long-term outcomes such as cancer incidence hard to assess ^[1]. The certainty of evidence was moderate at best and low for most of the cancers ^[1]. The analysis also did not show that GLP-1s reduce cancer risk, even though some prior observational studies did ^[1]. Absolute numbers of cancer cases in each group were not reported.

What happens next

Chiang said long-term randomized or observational studies with at least five years of follow-up and prespecified, standardized cancer endpoints are needed to clarify any risks or benefits of GLP-1s ^[1]. No specific studies or timelines for that work were announced ^[1].