You may have heard concerns about GLP-1 weight loss injections increasing the risk of thyroid cancer.
There's mounting evidence to suggest this isn't the case. Concerns were raised at an early stage based on rodent studies.
However, research from 2024 and 2025 has found little to suggest a link between GLP-1 drugs and thyroid cancer in humans.
And an even wider body of evidence points to potential health benefits beyond weight loss.
For instance, several studies have indicated that GLP-1 weight loss drugs like Wegovy and Mounjaro may reduce the risk of developing certain cancers.
Let's look at these studies in more detail.
GLP-1 drugs may reduce the risk of 10 obesity-related cancers in patients with diabetes
It's well established that obesity increases the risk of certain types of cancer. We also know that losing weight can reduce this risk.
GLP-1 drugs can help people with obesity lose weight – but it's unclear whether they have any link to these obesity-associated cancers (OACs).
One 2024 study set out to provide some clarity. The researchers looked at more than 1.6 million patients with type 2 diabetes. Their aim: to find out whether taking GLP-1 drugs had any impact on the risk of developing OACs.
The researchers found a 'significant risk reduction' in 10 OACs in patients taking GLP-1s, compared to patients taking only insulin. These OACs include colorectal, endometrial, gallbladder, kidney, liver, oesophageal, ovarian and pancreatic cancer.
GLP-1s may reduce OAC risk more than bariatric surgery
Another 2024 study compared the incidence of OACs in three patient groups:
Researchers found that both bariatric surgery patients and GLP-1 drug users saw a reduced risk of developing OACs compared to those who underwent no treatment. However, the risk reduction was higher in the GLP-1 group – 39% versus 22%.
GLP-1s may prevent certain cancers from growing
At least two studies have found evidence to suggest that GLP-1 drugs may help prevent cancerous tumours from growing.
The first, from 2014, found that liraglutide (Saxenda) "inhibited growth and promoted apoptosis in human pancreatic cancer cell lines". In other words, when exposed to liraglutide, the cancer cells stopped growing and died.
The second study, published in 2021, saw similar results with breast cancer cells. The researchers found that liraglutide exposure caused the cells to stop growing and spreading.
These results are promising – but they didn't involve human participants. Further studies are needed before we know whether the results can be replicated in real-life cancer patients.
SemaPen provides medical alternatives to gastric surgery. Why not learn more about our clinically proven weight loss treatment programmes?
Sources
1. Pasternak, B. et al. (2024) "Glucagon-like peptide 1 receptor agonist use and risk of thyroid cancer: Scandinavian cohort study" The BMJ, 385 https://doi.org/10.1136/bmj-2023-078225
2. Baxter, S.M. et al. (2025) "Glucagon-Like Peptide 1 Receptor Agonists and Risk of Thyroid Cancer: An International Multisite Cohort Study" Thyroid, 35(1) https://doi.org/10.1089/thy.2024.0387
3. Wang, L. et al. (2024) "Glucagon-Like Peptide 1 Receptor Agonists and 13 Obesity-Associated Cancers in Patients With Type 2 Diabetes" JAMA Network Open, 7(7) https://doi.org/10.1001/jamanetworkopen.2024.21305
4. Lin, C. et al. (2024) "Comparative risk of obesity-related cancer with glucagon-like protein-1 receptor agonists vs. bariatric surgery in patients with BMI ≥ 35" Journal of Clinical Oncology, 42 (suppl 16; abstr 10508) https://doi.org/10.1200/JCO.2024.42.16_suppl.10508
5. Zhao, H. et al. (2014) "Activation of glucagon-like peptide-1 receptor inhibits growth and promotes apoptosis of human pancreatic cancer cells in a cAMP-dependent manner" American Journal of Physiology-Endocrinology and Metabolism, 306(12)
https://doi.org/10.1152/ajpendo.00017.2014
6. Chequin, A. et al. (2021) "Antitumoral activity of liraglutide, a new DNMT inhibitor in breast cancer cells in vitro and in vivo" Chemico-Biological Interactions, 349 https://doi.org/10.1016/j.cbi.2021.109641
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