GLP-1s Like Ozempic, Wegovy Don’t Substantially Increase Thyroid Cancer Risk, Study Suggests

Topline

Popular diabetes and weight loss drugs like Ozempic and Wegovy, known as GLP-1 medications, were not found to cause a substantial increase in the risk of developing thyroid cancer, according to one of the biggest studies to explore the link, which is the latest research to dive into the highly debated topic.

Key Facts

Glucagon-like peptide-1 receptor agonists (GLP-1) are medications designed to manage obesity and type 2 diabetes by interacting with the hunger part of the brain to suppress the appetite, and lowering blood sugar and A1C.

The researchers looked at health data for 145,410 patients living in Denmark, Sweden and Norway who were prescribed GLP-1 medications like semaglutide—the generic name for Ozempic, Wegovy and Rybelsus—and liraglutide—the generic name for Saxenda and Victoza—and another 291,667 patients who were treated with DPP4 inhibitors, another type of diabetes drug.

Each group was compared and followed for an average of about four years: 76 participants treated with GLP-1 drugs and 184 participants treated with DPP4 inhibitors developed thyroid cancer, according to the study published Tuesday in BMJ.

The researchers determined that because the incidence rate was so low, GLP-1 use was not associated with a substantially increased risk of developing thyroid cancer, though they couldn’t “exclude a small increase in risk.”

The study also did a secondary analysis comparing 111,744 patients who took GLP-1 drugs to 149,179 patients who took another form of diabetes drug called SGLT2 inhibitors, and the results were consistent with the DPP4 inhibitor comparison.

Crucial Quote

“Our study covers a broad group of patients and provides strong support that GLP-1 analogues are not associated with an increased risk of thyroid cancer,” Björn Pasternak, study author and principal researcher at the Department of Medicine, Solna, at Karolinska Institutet in Sweden, said in a statement.

Contra

Some studies have found GLP-1 drugs may cause thyroid cancer in humans. Researchers looking at 47,000 participants—2,500 who already had thyroid cancer—found those who took GLP-1 drugs for between one to three years may have had an increased risk of all forms of thyroid cancer, compared to those who didn’t, according to a 2022 study. Mice and rats who were given GLP-1 drugs had higher incidence rates of developing thyroid C-cell tumors compared to those who weren’t, a study published in Endocrinology found. There were 468 reports of GLP-1-related thyroid cancer cases to the Food and Drug Administration between 2006 and 2023, including 18 deaths.

Key Background

Novo Nordisk, the makers of Ozempic, Wegovy, Saxenda and Victoza, list thyroid cancer as a potential side effect of each medicine and warn against use if a type of thyroid cancer called medullary thyroid carcinoma runs in the family. However, it does note the existence of studies that have found each medicine caused thyroid tumors in rats, though Novo states it’s unclear if this also happens in humans. The European Medicines Association reviewed recent research and said last October available evidence “does not support a causal association” between GLP-1 drugs and thyroid cancer. This came four months after the EMA raised a safety signal and said it’d look into whether GLP-1 drugs cause thyroid cancer. Researchers looked into the potential link between semaglutide and all types of cancers—including thyroid—and couldn’t find an increased risk. A 2022 research review examined whether semaglutide use increased the risk of thyroid cancer and other thyroid-related medical conditions like hypothyroidism and hyperthyroidism, and found there wasn’t an increased risk. A previous study also compared GLP-1 drugs to SGLT2 inhibitors and found no increased risk of thyroid cancer in the study population that took GLP-1 agonists, though the pool was much smaller than the BMJ study.