Glucagon-like peptide-1 receptor agonists and risk of thyroid cancer: A systematic review and meta-analysis of randomized controlled trials

Aim: To conduct a meta-analysis of randomized clinical trials (RCTs) to investigate whether there is an association between glucagon-like peptide-1 receptor agonist (GLP-1RA) treatment and thyroid cancer. Materials and methods: In this meta-analysis of RCTs, we included studies comparing a GLP-1RA with any comparator, lasting at least 52 weeks, and reporting the incidence of adverse events independently of the principal endpoint and population. All cases of thyroid cancer were collected. Results: We retrieved 64 trials, 26 of which reported at least one incident case of thyroid cancer. GLP-1RA treatment was associated with a significant increase in the risk of overall thyroid cancer (Mantel-Haenzel odds ratio [MH-OR] 1.52 [95% confidence interval {CI} 1.01, 2.29]; P = 0.04, I2  = 0%), with a fragility index of 1, and a 5-year number needed to harm of 1349. The association remained significant when including only trials lasting at least 104 weeks (MH-OR 1.76 [95% CI 1.00, 3.12]; P = 0.05). No significant association was found for papillary thyroid cancer (MH-OR 1.54 [95% CI 0.77, 3.06]; P = 0.22) or medullary thyroid cancer (MH-OR 1.44 [95% CI 0.23, 9.16]; P = 0.55). Conclusions: Our meta-analysis showed that GLP-1RA treatment could be associated with a moderate increase in relative risk for thyroid cancer in clinical trials, with a small increase in absolute risk. Studies of longer duration are required to assess the clinical implications of this finding.