From the Guidelines
Tirzepatide does not appear to increase cancer risk in humans, but caution is warranted due to animal studies showing thyroid C-cell tumors in rats, similar to other GLP-1 receptor agonists like semaglutide, as noted in the 2025 standards of care in diabetes 1. The Dual GIP and GLP-1 RA (SQ) section of the standards of care in diabetes mentions that the effect of tirzepatide on MACE, HF, and CKD is under investigation, but it does note potential effects on cancer risk, stating "Potential" under MASH effects, which may be related to the medication's impact on metabolic dysfunction-associated steatohepatitis 1. However, the most recent and highest quality study, the SURMOUNT-1 trial, showed a dose-dependent weight-loss benefit with tirzepatide in obese adults without diabetes over 72 weeks, with no significant increase in cancer risk reported 1. Some key points to consider when prescribing tirzepatide include:
- The medication is contraindicated in patients with personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2
- Patients should be monitored for symptoms like a lump in the neck, difficulty swallowing, or persistent hoarseness, and should contact their healthcare provider promptly if they experience any of these symptoms
- The cancer warning is primarily precautionary based on animal data, and the medication's benefits for managing type 2 diabetes and obesity typically outweigh this theoretical risk for most patients without specific thyroid cancer risk factors, as supported by the 2024 ESC guidelines for the management of chronic coronary syndromes 1.
From the FDA Drug Label
WARNING: RISK OF THYROID C-CELL TUMORS In both male and female rats, tirzepatide causes dose-dependent and treatment-duration-dependent thyroid C-cell tumors at clinically relevant exposures It is unknown whether MOUNJARO causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans as human relevance of tirzepatide-induced rodent thyroid C-cell tumors has not been determined [see Warnings and Precautions (5.1) and Nonclinical Toxicology (13. 1)]. MOUNJARO is contraindicated in patients with a personal or family history of MTC or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2) [see Contraindications (4)]. Counsel patients regarding the potential risk for MTC with the use of MOUNJARO and inform them of symptoms of thyroid tumors (e.g., a mass in the neck, dysphagia, dyspnea, persistent hoarseness). Routine monitoring of serum calcitonin or using thyroid ultrasound is of uncertain value for early detection of MTC in patients treated with MOUNJARO [see Contraindications (4) and Warnings and Precautions (5.1)].
The risk of cancer, specifically thyroid C-cell tumors including medullary thyroid carcinoma (MTC), with tirzepatide is unknown in humans. However, tirzepatide has been shown to cause dose-dependent and treatment-duration-dependent thyroid C-cell tumors in male and female rats at clinically relevant exposures 2.
Key points:
- Tirzepatide is contraindicated in patients with a personal or family history of MTC or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
- Patients should be counseled regarding the potential risk for MTC with the use of tirzepatide.
- Routine monitoring of serum calcitonin or using thyroid ultrasound is of uncertain value for early detection of MTC in patients treated with tirzepatide.
From the Research
Risk of Cancer for Tirzepatide
There is no direct evidence in the provided studies regarding the risk of cancer associated with tirzepatide.
- The studies primarily focus on the efficacy and safety of tirzepatide in patients with type 2 diabetes, comparing it to other treatments such as semaglutide, insulin glargine, and insulin degludec 3, 4, 5, 6.
- These studies report on adverse events, hypoglycemia, and other safety measures, but do not specifically address the risk of cancer 3, 4, 5, 6.
- One study examines the effects of semaglutide, tirzepatide, and metformin on β-cell maintenance and function under high-glucose-high-lipid conditions, but does not discuss cancer risk 7.
- Therefore, based on the provided evidence, there is no information available to assess the risk of cancer associated with tirzepatide.