A recent study has brought to light concerns surrounding the overdiagnosis of thyroid cancer in the United States, particularly among patients treated with glucagon-like peptide-1 receptor agonists (GLP-1s). These medications, used primarily for type 2 diabetes and weight management, have been linked to an increase in thyroid ultrasounds, potentially leading to more frequent diagnoses of thyroid cancer. Researchers examined trends in thyroid cancer incidence, metastasis, and mortality from 1975 to 2019 to better understand this phenomenon.
The findings suggest that thyroid cancer has been overdiagnosed for over a decade, likely due to advances in medical imaging technology such as CT scans and MRIs. These tools often detect thyroid nodules that are cancerous yet asymptomatic or clinically insignificant. According to experts, these screenings for unrelated conditions can inadvertently lead to a rise in thyroid cancer diagnoses.
Dr. McCoy, who was involved in the study, noted several limitations but emphasized the importance of thorough investigation when using GLP-1s.
“They all stem from wanting to do our due diligence and make sure that we use these medications safely and don’t miss something sinister,” – McCoy
In a deeper analysis, researchers observed an increased risk of thyroid cancer diagnosis within the first year of starting GLP-1s. However, they caution that cancer development typically takes longer, suggesting this early risk might not be significant. Past research found no additional risk of thyroid cancer in humans using GLP-1s. The suspicion arises mainly from a 2010 animal study where prolonged exposure to liraglutide, a GLP-1 receptor agonist, heightened the risk of medullary thyroid cancer in rodents.
“The evidence we have that raises suspicion is from animal studies that do not necessarily translate to people,” – McCoy
Dr. McCoy expressed confidence in the safety of GLP-1s for patients.
“I feel very confident telling my patients that they can safely take GLP-1s,” – McCoy
“If they are worried about thyroid cancer, it should be for reasons other than a GLP-1.” – McCoy
Richard Siegel, another expert in the field, mentioned that the discovery of small nodules often has little clinical impact on patients’ lives.
“Had they not been found, that wouldn’t have changed much of anything from the patient’s perspective,” – Richard Siegel
Despite a halt in the rise of thyroid cancer incidence post-2009, overdiagnosis rates remain unchanged. Dr. Zachary Zumsteg elaborated on this trend:
“What we found was that although the incidence of thyroid cancer stopped rising after 2009, the rates of overdiagnosed thyroid cancers have essentially stayed the same,” – Zachary Zumsteg
The low mortality rate associated with thyroid cancer further complicates the issue of overdiagnosis.
“Mortality from thyroid cancer as a whole continues to be very, very low,” – Richard Siegel
Siegel emphasized the role of technology in this phenomenon:
“Ultimately, you’re getting a lot of early diagnosis of nodules,” – Richard Siegel
“I tell my patients, ‘We’re victims of our own technology,’” – Richard Siegel
The study also explored other risk factors that may predispose individuals to thyroid cancer. A family history of the disease or genetic disorders like multiple endocrine neoplasia type 2 (MEN2) can increase susceptibility. Despite these concerns, evidence linking GLP-1s directly to thyroid cancer remains inconclusive, primarily because animal study findings do not always apply to humans.
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