A new Scandinavian study published Wednesday found no conclusive evidence to support the link between GLP-1 receptor agonists and an increased risk of thyroid cancer.
GLP-1 receptor agonists—a popular drug class that includes Novo Nordisk’s Ozempic (semaglutide) and Victoza (liraglutide)—do not appear to increase the risk of thyroid cancer, according to a new study published Wednesday in The BMJ.
The Scandinavian study, led by researchers at Swedish medical university Karolinska Institutet, drew from national registry data in Denmark, Norway and Sweden. The researchers looked at around 145,000 patients who had been treated with GLP-1s, primarily semaglutide and liraglutide, which is also sold by Novo under the brand name Saxenda. The study used data from more than 290,000 patients receiving other diabetes treatments, primarily DPP4 inhibitors.
Over an average follow-up of just under four years, patients treated with GLP-1 receptor agonists did not see a significantly higher risk of developing thyroid cancer. This result remained consistent when GLP-1 analogs were compared with SGLT2 inhibitors, another common class of diabetes medication.
“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, principal researcher at the Department of Medicine at Karolinska Institutet, said in a statement.
At the same time, the researchers were quick to point out that their findings do not definitively establish that GLP-1 agents are completely free of thyroid cancer risk.
“We cannot rule out that the risk of certain subtypes of thyroid cancer is increased in smaller patient groups that we could not study here,” Peter Ueda, assistant professor at the Department of Medicine at Karolinska Institutet, said in a statement. Patients who are more susceptible to congenital medullary thyroid cancer, for instance, are “advised against using these drugs.”
GLP-1 receptor agonists are a top-selling class of diabetes and obesity medications that work by mimicking the GLP-1 hormone to induce the production and secretion of insulin from the pancreas. Novo’s semaglutide and Lilly’s tirzepatide currently dominate the GLP-1 space, with the two companies projected to control around 80% of the multibillion-dollar market by 2030.
Amid soaring demand, however, GLP-1s have been flagged for several potential safety issues. In July 2023, the European Medicines Agency (EMA) launched an investigation into the drug class over a potential association with thyroid cancer. A few months later, however, the regulator found no conclusive evidence to support the link.
GLP-1 therapies are also being reviewed for their potential risk of increasing suicidal ideation and self-harm. The EMA kicked off its probe in July 2023 and its Pharmacovigilance Risk Assessment Committee is scheduled to continue discussions this week.
The FDA in January 2024 also initiated an investigation into the suicidal ideation and self-harm risks of GLP-1 analogs, but a week later found no evidence to support such an association.
Tristan Manalac is an independent science writer based in Metro Manila, Philippines. Reach out to him on LinkedIn or email him at tristan@tristanmanalac.com or tristan.manalac@biospace.com.
