Thyroid Cancer Overdiagnosis in the U.S.—Is Ozempic Exacerbating the Issue?

A recent study has unearthed a striking correlation: the meteoric rise of weight loss drugs like Ozempic and Wegovy may be fueling an already troubling epidemic of thyroid cancer overdiagnosis.

Published in JAMA Otolaryngology—Head & Neck Surgery this January, the research suggests that individuals prescribed glucagon-like peptide-1 (GLP-1) receptor agonists are diagnosed with thyroid cancer at a significantly higher rate than the general population.

But here’s the kicker—rather than these medications instigating malignancy, the surge in diagnoses likely stems from increased scrutiny. The prevailing hypothesis? Patients on GLP-1s are subjected to more screenings due to prior research hinting at a possible cancer link, explains lead author Rozalina McCoy, MD, associate professor and associate division chief for clinical research in the Division of Endocrinology, Diabetes, and Nutrition at the University of Maryland School of Medicine.

“We’re uncovering more cases—not necessarily because cancer is more prevalent, but because we’re actively searching for it,” McCoy noted.

Such screenings frequently detect benign thyroid nodules, leading to superfluous cancer diagnoses. This phenomenon isn’t exclusive to GLP-1 users. A February study highlighted that thyroid cancer has been overdiagnosed for over a decade, a consequence of increased medical imaging.

“What we discovered is that while the overall incidence of thyroid cancer plateaued after 2009, the rate of overdiagnosed cases remains alarmingly steady,” remarked Zachary Zumsteg, MD, an associate professor at Cedars-Sinai Cancer Institute and senior author of the study. “Despite greater awareness, overdiagnosis persists at peak levels.”

The GLP-1 and Thyroid Cancer Connection

The JAMA researchers initially embarked on their study to reassess whether GLP-1 medications inherently heightened thyroid cancer risk, McCoy explained.

A 2010 animal study had already sent shockwaves through the medical community, revealing that prolonged exposure to liraglutide—an early GLP-1 receptor agonist—elevated rodents’ risk of medullary thyroid cancer, an exceptionally rare form accounting for just 3% to 4% of human cases. As a result, GLP-1 drugs carry a black box warning.

However, subsequent human trials failed to substantiate any substantial uptick in thyroid cancer risk among GLP-1 users.

To probe further, McCoy and her team scrutinized data from 351,913 adults who had newly filled prescriptions for various medications, including GLP-1s. The cohort shared key characteristics: all had type 2 diabetes, were at moderate risk for heart disease, and had no prior history of thyroid cancer.

“At first glance, GLP-1s seemed to slightly amplify the likelihood of a thyroid cancer diagnosis,” McCoy acknowledged. “But upon closer inspection, this increase only manifested within the first year of treatment—a red flag, considering that malignancies typically take years to develop.”

To unravel this mystery, the researchers examined whether GLP-1 users underwent thyroid screenings at a disproportionate rate. The results? Striking. “Patients on GLP-1s were far more likely to receive thyroid ultrasounds,” McCoy revealed.

Their conclusion: the spike in diagnoses wasn’t due to an actual increase in cancer but rather the detection of pre-existing, non-threatening nodules.

However, the study had limitations, McCoy cautioned. Detailed patient histories—including specific risk factors for thyroid cancer—were unavailable. Additionally, researchers lacked insights into why certain patients were screened, how they were diagnosed, or the type and stage of cancer identified.

The Broader Overdiagnosis Epidemic

Beyond the GLP-1 debate, thyroid cancer overdiagnosis has become an entrenched issue, primarily driven by widespread medical imaging like CT scans and MRIs.

Often, screenings performed for unrelated conditions incidentally unearth asymptomatic thyroid nodules. Though technically cancerous, these nodules are frequently harmless.

“Had they gone undetected, nothing about the patient’s health trajectory would have changed,” explained Richard Siegel, MD, an endocrinologist and co-director of the Diabetes and Lipid Center at Tufts Medical Center.

Mortality from thyroid cancer remains exceptionally low, Siegel emphasized. Although survival rates vary based on type and stage, papillary thyroid cancer—the most prevalent form—boasts a staggering 99.5% five-year survival rate. “What we’re witnessing is an influx of early-stage diagnoses that likely never would have posed a clinical threat,” Siegel added.

McCoy suspects that a similar dynamic is at play among GLP-1 users. The presence of a black box warning may be fostering heightened vigilance among both physicians and patients, driving an uptick in screenings and, consequently, benign diagnoses.

“Our intentions are noble—we aim to prescribe these medications responsibly and ensure patient safety,” McCoy said. “But in doing so, we may be inadvertently fueling an overdiagnosis epidemic.”

Should GLP-1 Users Worry About Thyroid Cancer?

The consensus among experts? Unlikely.

“The concerns stem from animal studies, which don’t necessarily translate to humans,” McCoy clarified. “Based on available evidence, I confidently reassure my patients that GLP-1s are safe.”

Individuals at higher risk for thyroid cancer typically have a strong family history of the disease or suffer from rare genetic disorders like multiple endocrine neoplasia type 2 (MEN2), Siegel noted. Exposure to high levels of radiation is another well-documented risk factor, McCoy added.

For those apprehensive about their thyroid health, experts stress the importance of consulting a healthcare provider. Nevertheless, both for GLP-1 users and the general population, the absolute risk remains minimal.

“I always tell my patients: ‘We’re victims of our own technology,’” Siegel mused. “Advancements in medical imaging are uncovering conditions that, in many cases, never needed to be found in the first place.”