SCOTTSDALE, AZ — While most of the research on the role of GLP-1 receptor agonists (RAs) in thyroid cancer has focused on their potential to trigger such cancer, new research found that among patients with existing differentiated thyroid cancer (DTC), treatment with GLP-1 RAs did not increase the risk of recurrence or progression.

“We evaluated for the first time the association between GLP-1 RA exposure and risk of thyroid cancer recurrence/progression on a population with a prior or current diagnosis of differentiated thyroid cancer,” first author Armando Patrizio, MD, of Pisa University Hospital in Italy, told Medscape Medical News. 

“We did not find a significant association between GLP-1 RAs and recurrent/progressive DTC, so based on the current evidence, these drugs should not be denied in patients with obesity and/or diabetes when they are clinically indicated,” he said of the study, which was presented at the 2025 American Thyroid Association (ATA) Annual Meeting in Scottsdale, Arizona.

The risk of obesity is known to be increased in thyroid cancer, therefore these patients may benefit not only from the weight-loss and diabetes effects of GLP-1 RAs but from the known cardiometabolic and kidney protective attributes.

However, GLP-1s are contraindicated in patients with a personal or family history of medullary thyroid cancer, despite most evidence on the association derived from mouse studies, and there is also conflicting evidence regarding the effects of the drugs in follicular cell-derived thyroid cancer.

GLP-1s in Patients With DTC

To evaluate the effects of GLP-1 RAs in patients with a previous or active diagnosis of DTC, the most common type of thyroid cancer, Patrizio and colleagues conducted a retrospective, observational cohort study of 536 patients with DTC who had been treated at Memorial Sloan Kettering Cancer Center in New York and exposed to GLP-1 RAs between 2005 and 2025.

These patients were matched 1:1 with a control group of 536 patients with DTC who had never been exposed to GLP-1 RAs. The patient pairs were matched based on date of DTC diagnosis, tumor stage, BMI, and diabetes status.

In the combined cohort of 1072 patients, the median age was 49, and 71% were female. The patients had a mean BMI of 35; 54% had diabetes.

The majority (84%) had stage 1 disease, and 58% were of ATA intermediate or high risk for structural recurrence.

The median exposure to GLP-1 RAs was 16 months, and 61% of patients received therapy for more than a year. 

With patients being followed for a median of 68 months, a univariate analysis showed no significant association between GLP-1 RAs and an increased risk of disease recurrence or progression.

A further multivariate analysis showed a trend toward a reduced risk of recurrence or progression (hazard ratio [HR], 0.73), after adjusting for age, tumor size, lymph node metastasis, radioactive iodine therapy, and diabetes.

Key factors associated with disease recurrence or progression included ATA high or intermediate risk versus low, treatment with radioiodine therapy, and age over 55 (all P < .0001).

Patrizio noted that the findings are consistent with what has been observed in the clinical setting.

“In practice, we do not find evident progression of disease among patients exposed to GLP-1 RAs, so it was not surprising to find no significant association between the drugs and recurrence or progression of well-differentiated thyroid cancer.”

He added that the trend of a decreased risk of recurrence or progression observed should be interpreted with caution, “because we did not find a significant association of GLP-1RA with recurrence or progression of disease in sensitivity analyses comparing pairs of patients exposed and not exposed to GLP-1RAs with the same duration of follow-up.” 

Findings Are “Heartening” — With Caveats

Commenting on the current study, Ashish Chintakuntlawar, MBBS, PhD, a professor of medicine in the Division of Hematology-Medical Oncology at the Mayo Clinic, in Phoenix, commended the study’s relatively large number of patients and “excellent design,” noting some key limitations.

“It is heartening to see that these relatively commonly used drugs do not have any detrimental effect on the prognosis of differentiated thyroid cancer,” Chintakuntlawar told Medscape Medical News. “However, I would caution as this is still relatively short follow-up and hence continued monitoring, observation, and continued research on large scale population is required.”

He added that the DTCs included in the study “have excellent prognosis to begin with, and hence any small detrimental effect could get diluted.”

While intriguing, Chintakuntlawar agreed that the finding of a trend toward improved outcomes with GLP-1s “should also be taken with caution, as it is not statistically significant and the study was not designed for it.”

Important Limitations Common in Studies on Thyroid Cancer/GLP-1 Connection 

The question of a potential link between GLP-1s and thyroid cancer has prompted a plethora of studies in the years since the drugs exploded onto the market, with findings ranging from one recent meta-analysis showing an odds ratio of 1.55 for an increased thyroid cancer risk, to another study suggesting the potential to lower cancer incidence with GLP-1s, to still another study showing an increased risk — but only in the first year, suggesting the increased reports are likely the result of increased neck ultrasounds among newly prescribed patients, explained Bryan R. Haugen, MD, a professor of medicine and pathology at the University of Colorado School of Medicine, in Aurora, in addressing the ongoing issue at the meeting’s Year in Review session.

Importantly, many studies have had limitations such as not including patients with medullary thyroid cancer, the rare cancer that is the subject of the FDA warning; not including important design features such as latency assessments or cohorts of patients on tirzepatide, a dual agonist, or the novel drug retatrutide, a triple agonist; and not having long-term follow-up, Haugen noted.

“My summary [of the conflicting evidence] is I think it is unlikely that there is an association between GLP-1 RAs and DTC,” he concluded. As the one study shows, “the early detection of small disease is likely due to [greater ultrasound testing] in some of the patients.” 

Ultimately, “I think the cardiometabolic effects of the drugs far outweigh the potential risks,” he said. 

Patrizio and Chintakuntlawar had no disclosures to report. Haugen is a clinical liaison for ThyroSeq and Sonic Healthcare USA and has received research support from Veracyte.