Glucagon-like peptide-1 (GLP-1) receptor agonists are medications used to control blood glucose levels in people with type 2 diabetes, and may also be prescribed for those with obesity to help with weight loss. Early studies suggested a link between GLP-1 agonists and an increased risk of thyroid cancer. However, a recent large-scale Scandinavian study found no significant increase in thyroid cancer risk in those taking GLP-1 agonists compared to other type 2 diabetes treatments. These drugs work by increasing insulin release, suppressing glucagon release, improving insulin sensitivity, slowing gastric emptying, and increasing feelings of fullness after eating.
Both the FDA and NICE have approved some GLP-1 agonists for weight loss in individuals with obesity and related health conditions. Use of these drugs has increased significantly since their approval, though concerns about an increased risk of thyroid cancer have been raised in some studies. The recent large-scale study found no significant increase in thyroid cancer risk for those on GLP-1 agonists compared to those on DPP4 inhibitors, which have no known thyroid cancer risk. This study, published in The BMJ, used data on over 145,000 people treated with GLP-1 agonists and almost 292,000 people treated with DPP4 inhibitors from Norway, Sweden, and Denmark.
Researchers followed participants for a mean of 3.9 years in the GLP-1 group and 5.4 years in the DPP4 group, identifying cases of thyroid cancer using national cancer registers. The relative risk for developing thyroid cancer while on GLP-1 agonists was found to be increased by no more than 31%. While this may seem concerning, bariatric surgeon Mir Ali explained that this increase is relatively low and indicates a low risk of developing thyroid cancer due to these medications. However, caution should still be taken in patients with hereditary thyroid cancer syndromes.
Thyroid cancer is more common in women than men but is still considered a relatively rare form of cancer. Incidence rates are low, with a slight increase in relative risk due to GLP-1 agonists still indicating a very low likelihood of developing the disease. Alongside controlling blood glucose levels and promoting weight loss, GLP-1 agonists have additional health benefits, including cardiovascular benefits, reducing blood pressure and inflammation, and potentially slowing the progression of chronic kidney disease in people with type 2 diabetes.
Though GLP-1 agonists have common side effects such as gastrointestinal symptoms and irritation at injection sites, these are generally mild and usually diminish over time. The recent study should reassure individuals taking these medications that the risk of thyroid cancer is very low, as previous concerns were primarily based on animal studies. Ali believes that this study helps demonstrate the safety of GLP-1 agonists and their low associated risk of thyroid cancer.
