From the Desk of Dr. Z: AgelessRx Co-founder and Chief Medical Officer, Dr. Sajad Zalzala offers his insightful perspective on topics related to longevity. With a wealth of experience and a deep-seated passion for disease prevention and extending healthy lifespans, Dr. Z is dedicated to sharing his knowledge on the secrets to longevity. Today, he shares his knowledge on whether GLP-1 medications actually increase the risk of thyroid cancer.
Here’s what we’ll cover in this blog post:
- Do GLP-1 medications increase the risk of thyroid cancer
- Where this concern oiginated
- What human studies show
GLP-1 receptor agonists, such as Semaglutide and Tirzepatide, have become popular treatments for type 2 diabetes and weight management.
However, some patients have concerns about the potential risks these medications pose for thyroid cancer. In this article, I’ll explore the origins of these concerns, examine why they may not apply to humans, and discuss what the data shows about thyroid cancer risks in people using GLP-1 medications.
What Are GLP-1 Receptor Agonists?
GLP-1 receptor agonists are a class of drugs that mimic the action of glucagon-like peptide-1 (GLP-1), a hormone that stimulates insulin secretion and inhibits glucagon release. These drugs are used originally in the treatment of type 2 diabetes and are now gaining attention for their role in weight management.
Where Do Thyroid Cancer Concerns Originate?
The concerns about a potential link between GLP-1 receptor agonists and thyroid cancer largely stem from early animal studies. In these studies, rats and mice treated with GLP-1 medications developed C-cell tumors in the thyroid gland, a type of tumor that can develop into medullary thyroid carcinoma (MTC). C-cells in the thyroid produce calcitonin, a hormone that helps regulate calcium levels.
However, it’s important to note that the thyroid physiology of rodents differs significantly from that of humans, especially when it comes to the density of GLP-1 receptors. This leads us to why these concerns might not translate to human risk.
Why These Concerns May Not Apply to Humans
Although these animal studies raised red flags, human physiology suggests that the findings in rodents may not apply to humans.
- Rodent Thyroid Differences: Rats and mice have a higher number of GLP-1 receptors on their thyroid C-cells compared to humans, making their thyroids more sensitive to the hormone. This heightened sensitivity likely explains the increase in tumor formation in the animals. In humans, C-cells contain far fewer GLP-1 receptors, which suggests a much lower risk for similar outcomes.
- Human Pharmacology Studies: To date, no clinical trials have conclusively linked GLP-1 receptor agonists to thyroid cancer in humans. Several large-scale human studies, including SUSTAIN-6 for semaglutide and LEADER for liraglutide, have found no significant increase in the risk of MTC or other thyroid cancers compared to placebo groups.
What Human Studies Show
Reassuringly, the data from human trials does not support the same level of concern that arose from rodent studies. Here are some key takeaways from the available human data:
- Clinical Trial Data: Human trials such as SUSTAIN-6 and LEADER have not demonstrated an increase in thyroid cancer diagnoses among patients using GLP-1 medications. These trials were specifically monitored for cancer-related adverse effects and found no notable differences in thyroid cancer incidence between the treatment and control groups .
- Real-World Data: Post-marketing surveillance and real-world studies continue to monitor the long-term safety of GLP-1 drugs. These studies have similarly shown no significant increase in thyroid cancer rates compared to the general population.
The current evidence supports the idea that GLP-1 medications are safe for most people when it comes to thyroid cancer risks. However, some individuals may need to take additional precautions.
When to Be Cautious
Although GLP-1 receptor agonists appear to be safe for most individuals, there are exceptions. Certain populations may need to exercise caution, particularly those with specific thyroid conditions.
- Personal History of Medullary Thyroid Carcinoma (MTC): People with a personal history of MTC should generally not use GLP-1 receptor agonists. Given the theoretical risk observed in animal studies and the seriousness of MTC, these individuals are not typically candidates for treatment through telehealth platforms, where an in-depth, in-person assessment might be more appropriate.
- Multiple Endocrine Neoplasia Syndrome (MEN2): Individuals with MEN2 are at increased risk for developing MTC and should also avoid GLP-1 medications. While human studies have not shown a direct link, the elevated risk for those with MEN2 makes GLP-1 receptor agonists a poor choice in these cases.
- Family History of MTC or MEN2: For people with a family history of MTC or MEN2 but no personal diagnosis, it may still be safe to proceed with caution. The risk may be lower, but it’s important to have an in-depth discussion with a healthcare provider to weigh the risks and benefits. Regular monitoring and personalized care can help guide these decisions.
Should You Be Concerned?
For most people, the available human data does not support the same concerns that arose from rodent studies regarding GLP-1 receptor agonists and thyroid cancer. However, individuals with a personal history of medullary thyroid carcinoma or MEN2 should avoid these medications, and those with a family history should consult with a specialist before proceeding.
GLP-1 medications remain a safe and effective option for managing type 2 diabetes and obesity for the majority of the population, but it’s crucial to evaluate each patient’s risk profile before starting treatment.
Note: The above statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.