GLP-1 and Thyroid Cancer Link Lacks Evidence, White Paper Finds

A new white paper issued by the Clayman Thyroid Center in Tampa, Florida, concludes that popular GLP-1 receptor agonists prescribed for weight control demonstrate that the agents show no cause, or have an effect upon, the most common types of thyroid cancer based on the best available human data.

The white paper, titled “Do GLP-1 Weight-Loss Shots Like Ozempic and Mounjaro Really Raise Thyroid Cancer Risk? The Latest Facts Explained,” examines mechanistic research, clinical trials, large population studies, and real-world clinical experience. Its central message: much of the current fear is driven by misunderstanding rather than strong human evidence.

The paper’s authors, Gary L. Clayman, MD, FACS, FACE, and Rashmi Roy, MD, FACS, note that thyroid cancer is not a single disease. The FDA boxed warning that appears on these drugs is specific to medullary thyroid carcinoma, a rare neuroendocrine tumor that accounts for less than 5% of all thyroid malignancies. That warning, the authors emphasize, was never intended to apply to papillary, follicular, or Oncocytic Hürthle cell thyroid cancers, which together constitute the vast majority of cases seen in community practice. For patients with these more common forms of thyroid cancers, decisions about GLP-1 therapy should be individualized, considering metabolic benefits and overall health goals.

The paper emphasizes, however, that medullary thyroid carcinoma and its hereditary syndrome, Multiple Endocrine Neoplasia type 2, remain problematic. The white paper affirms that GLP-1 receptor agonists remain contraindicated in patients with a personal or family history of these conditions, consistent with the existing FDA labeling. For this small subset of patients, caution remains appropriate.

“Thyroid cancer is not a single disease, and that distinction matters,” Gary L. Clayman, MD, FACS, FACE, senior author of the white paper, said in a release. “The FDA boxed warning tied to GLP-1 medications is specific to a rare cancer called medullary thyroid carcinoma. It does not apply to the common thyroid cancers that account for more than 95% of cases.”

Study Data

According to the paper, major international cohort studies and meta-analyses have not found increased thyroid cancer rates among GLP-1 users. Some studies showing possible "associations" may be explained by detection bias. Patients on GLP-1 therapy often have more medical visits, imaging, and specialist care, which can increase the likelihood of discovering pre-existing thyroid nodules or small cancers that might otherwise remain undetected.

“When diagnoses rise shortly after starting a medication, that pattern often reflects finding something that was already there,” Rashmi Roy, MD, FACS, coauthor of the white paper, said. “That is very different from a drug actually causing a new cancer.”

The question is not whether GLP-1 drugs carry any thyroid cancer signal. They do, but it is narrow, rare, and mechanistically distinct from the cancers that fill most oncology schedules. The larger takeaway, and the one the Clayman authors intend, is that the evidence tying these blockbuster drugs to common thyroid malignancies is, on close examination, unconvincing.

The Clayman Thyroid Center treats approximately 2000 patients with thyroid cancer each year and is among the highest-volume thyroid centers in the world.

REFERENCE

Clayman GL, Roy R. Do GLP-1 weight-loss shots like Ozempic and Mounjaro really raise thyroid cancer risk? The latest facts explained. White paper. February 2026. Accessed February 11, 2026. https://www.thyroidcancer.com/files/GLP1s-Thyroid-Cancer.pdf