GLP-1 agonists are a class of medications that help manage blood sugar levels in people with Type 2 diabetes and can also help treat obesity.
There is ongoing research and debate about the potential connection between GLP-1 (Glucagon-like peptide-1) and thyroid cancer. Some studies have suggested a possible link between the use of GLP-1-based therapies for diabetes and an increased risk of thyroid cancer. However, the evidence is not definitive, and more research is needed to determine the relationship between GLP-1 and thyroid cancer.
Currently, GLP-1 receptor agonists are contraindicated in patients with medullary thyroid cancer and patients with multiple endocrine neoplasia 2 (MEN-2). Caution is also recommended in patients with a family history of thyroid cancer and those with a genetic predisposition for papillary or follicular thyroid cancer.
GLP-1 receptor agonists can be used safely in patients with thyroid cancers derived from thyroid follicular epithelium (papillary and follicular thyroid cancer).
Types of Thyroid Cancer
The four types of thyroid cancer include medullary, papillary, follicular, and anaplastic.
GLP-1 receptor agonists are contraindicated with medullary thyroid cancer. This type of cancer is extremely rare in humans. From 1992 to 2006, 976 cases were diagnosed in the United States, compared with 36, 583 cases of papillary thyroid cancer, and 4,560 cases of follicular thyroid cancer. People of Hispanic descent have the highest incidence rates of medullary thyroid carcinoma. Cleveland Clinic Journal of Medicine March 2015, 82 (3) 142-144; DOI: https://doi.org/10.3949/ccjm.81a.13066.
Healthy Human C cells DO NOT express GLP-1 receptors
GLP-1 receptor agonists receptors are expressed in the lung; kidney; stomach; heart; intestine; α, β, and d cells of the pancreatic islets; and multiple regions of the CNS. Daniel J. Drucker, in Physiology of the Gastrointestinal Tract (Fourth Edition), 2006.
Of relevance, the parafollicular cells (or C-Cells) of the thyroid express receptors if cancer develops. These are the cells involved in medullary thyroid cancer.
Animal experiments with mice and rats revealed a higher incidence of thyroid C-Cell tumors in animals given GLP-1 analogs. Sustained activation of these receptors caused C-cell hyperplasia and resulted in medullary thyroid cancer, though medullary thyroid cancer also occurred in animals who received a placebo.
An important point to consider is that healthy human C Cells DO NOT express GLP-1 receptors at all. Noting the substantial differences in the biology of rodent vs human thyroid GLP-1 receptor systems is extremely important in making conclusions regarding the risk of developing medullary thyroid cancer with GLP-1 therapy.
Currently, the US Food and Drug Administration is not recommending additional monitoring such as calcitonin level or ultrasound imaging for screening patients taking GLP-1 agonists. Cleveland Clinic Journal of Medicine March 2015, 82 (3) 142-144; DOI: https://doi.org/10.3949/ccjm.81a.13066.
The evidence linking GLP-1 to thyroid cancer is not conclusive. While some studies have indicated a potential connection, more research is required to establish a definitive relationship. The risk of thyroid cancer associated with GLP-1 use may vary among individuals based on their medical history, underlying health conditions, and other factors.
Ongoing research in this area aims to further understand the relationship between GLP-1 receptor agonists and thyroid cancer, which may lead to clearer insights and guidelines in the future.
Ultimately, it is important to have open communication with your healthcare provider regarding any concerns you have about GLP-1 and thyroid cancer. They can offer tailored advice and support to help you make informed decisions about your health and treatment options.
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