In 2024, an analysis published in shook up a question that most assumed closed. After reviewing the follow-up of 1,651,452 patients with type 2 diabetes for up to 15 years, the researchers found that those who received GLP-1 receptor agonists had a significantly lower risk of developing 10 of the 13 obesity-associated cancers, compared to those who received insulin.
That news came after years of opposite concern. When GLP-1 began to be used on a large scale, the first regulatory signals came loaded with warnings about oncogenic potential — specifically medullary thyroid carcinoma, based on studies with rodents. The public asked if these peptides could cause cancer. More recent evidence tells a more complex story: in humans, for most obesity-associated cancers, GLP-1 is associated with lower risk, not higher.
In this guide we review what recent clinical evidence says about the relationship between GLP-1 and cancer, what mechanisms could explain it, what is happening with the thyroid controversy, and where are the honest limits of what we know to date.
The Hinge Study: Wang and Collaborators, 2024
Wang L., Xu R., Kaelber D.C. and Berger N.A. published in 2024 (volume 7, issue 7, e2421305) one of the largest retrospective cohorts ever analyzed on this question. They used the TriNetX network, which aggregates more than 113 million electronic health records in the United States. They filtered 1,651,452 patients with type 2 diabetes without a previous diagnosis of cancer between 2005 and 2018, and followed their evolution for up to 15 years.
They compared two large groups: patients treated with GLP-1 (semaglutide, liraglutide, dulaglutide, exenatide) versus patients treated with insulin. They specifically examined the 13 cancers that the International Agency for Research on Cancer (IARC) has epidemiologically linked to obesity.
The central finding: In 10 of the 13 cancers analyzed, patients treated with GLP-1 had a significantly lower risk than patients treated with insulin. The reductions, expressed as Hazard Ratio (HR), were in some cases substantial.
The 10 Cancers with Significant Reduction
The results ordered by magnitude of reduction versus insulin:
→ Gallbladder cancerHR 0,35 — reducción del 65% del riesgo.
→ MeningiomaHR 0,37 — reducción del 63% del riesgo.
→ Pancreatic cancerHR 0.41 — 59% risk reduction. Particularly relevant due to the historical regulatory concern about pancreatitis and pancreatic cancer associated with this class.
→ HepatocarcinomaHR 0.47 — 53% risk reduction. Consistent with a subsequent analysis by the same group published in 2024.
→ Ovarian cancerHR 0,52 — reducción del 48% del riesgo.
→ Cáncer colorrectalHR 0,54 — reducción del 46% del riesgo.
→ Mieloma múltipleHR 0,59 — reducción del 41% del riesgo.
→ Esophageal cancerHR 0,60 — reducción del 40% del riesgo.
→ Endometrial cancerHR 0,74 — reducción del 26% del riesgo.
→ Kidney cancerHR 0,76 — reducción del 24% del riesgo.
Three cancers did not show a statistically significant difference: postmenopausal breast (HR 1.07), thyroid (HR 0.99) and stomach (HR 0.73, not significant). The “neither increase nor decrease” signal in thyroid cancer is relevant because it directly addresses the historical regulatory concern.
¿Por Qué Funcionan? Tres Mecanismos Probables
The association the study found does not establish causality. But there are plausible mechanisms that could explain it, and most of the scientific community sees them as complementary rather than exclusive.
→ Reduction of systemic metabolic pressure
Sustained weight loss decreases visceral adiposity, reduces insulin resistance and lowers IGF-1 (insulin-like growth factor) levels. Elevated insulin/IGF-1 axis is linked to uncontrolled cell proliferation in multiple types of cancer associated with obesity. Less fuel available, less proliferation.
→ Modulation of systemic inflammation
Wong C.K., Drucker D.J. and collaborators published a decisive work in in 2024: activation of the central GLP-1 receptor modulates low-grade inflammation via adrenergic and opioid signaling. In clinical trials such as STEP-HFpEF and SUMMIT, high-sensitivity CRP falls between 38% and 43%, partially independent of weight loss. Chronic low-grade inflammation is one of the areas where tumors associated with obesity proliferate.
→ Direct effects on the tumor microenvironment
Cencioni C. and collaborators published inin 2025 preclinical data on semaglutide in pancreatic cancer models: the drug remodeled tumor-associated fibroblasts, reduced proline hydroxylation of collagen and favored T lymphocyte infiltration. It is a direct mechanism on the tumor stroma, not mediated by weight loss. It is in the preclinical phase, but it opens an interesting line.
Un Detalle Crítico: vs Metformina No Hay Beneficio Adicional
The Wang 2024 study made an additional less publicized but analytically important comparison: GLP-1 versus metformin. In that comparison, GLP-1 did not show additional reduction in cancer compared to metformin.
This observation qualifies the interpretation. It does not mean that GLP-1 does not work — it means that it probably acts on metabolic pathways shared with metformin (better insulin sensitivity, reduction of the IGF-1 axis, possible antiproliferative effects via AMPK). In other words, GLP-1 appears to reduce the risk of obesity-associated cancer for metabolic reasons similar to those of metformin, not for a unique antitumor mechanism.
This is important to avoid inflated messages. GLP-1 does not appear to be chemopreventive in itself. They reduce the risk of cancers associated with obesity probably because they improve the metabolic environment that these cancers take advantage of.
Pancreatic Cancer: from Suspicion to Benefit
For years, one of the strongest concerns surrounding GLP-1 was its potential link with pancreatitis and, by extension, pancreatic cancer. Early pharmacovigilance reports generated signals that led to extensive investigations.
The current data is reassuring. A meta-analysis presented at ASCO GI 2026 by Tangella A.V. and colleagues in the Journal of Clinical Oncology showed a pooled Hazard Ratio of 0.79 (95% CI 0.72–0.86) for pancreatic cancer in GLP-1 users — a 21% risk reduction. The historical signal of increasing pancreatic cancer is discarded as causal by regulatory agencies, and replaced by consistent evidence of lower risk.
The meta-analysis by Wen et al in2025, on randomized controlled trials, also did not show a significant increase in acute pancreatitis (OR 1.05; CI 0.78–1.40). The conclusion is that the historical risk was probably overestimated due to biases in initial pharmacovigilance.
Hepatocarcinoma: Protección Hepática Integral
The liver is one of the organs where GLP-1 shows multiple benefits. They reduce steatosis, improve fibrosis (as demonstrated by the ESSENCE trial for MASH published in 2025) and, based on observational evidence, could reduce the risk of hepatocellular carcinoma.
Wang L. et al published in 2024 an additional analysis in patients with type 2 diabetes: users of GLP-1 versus sulfonylureas had HR 0.78 (CI 0.65–0.93) for hepatocellular carcinoma. Compared to metformin, however, the result was not significant (HR 0.99) — it reinforces the pattern mentioned above: GLP-1 acts on metabolic pathways shared with metformin, not on an exclusive antitumor axis.
The same analysis showed a lower incidence of hepatic decompensation in GLP-1 users, consistent with the findings of ESSENCE and SYNERGY-NASH on fibrosis reversal and histological improvement in MASH.
The Thyroid Cancer Controversy: Separating Rodents from Humans
No GLP-1 topic has generated more confusion than thyroid cancer. It is worth understanding precisely.
The origin of the warning
Bjerre Knudsen L. and collaborators published in in 2013 the toxicology studies that gave rise to the . In rats and mice, high doses of liraglutide and exenatide produced dose-dependent thyroid C-cell hyperplasia and medullary carcinoma. The FDA precautionarily required the warning for the entire class.
Por qué no se traslada linealmente a humanos
The same work quantified the difference between species, and that difference is decisive: the density of thyroid C cells in mice is 22 times greater than in humans, and in rats it is 45 times greater. Furthermore, GLP-1 receptor mRNA transcripts in human C cells are 14 to 21 times lower than in rat C cells.
In other words: the biological substrate where the tumor appears in rodents exists in humans on a radically smaller scale. What is observed in one species does not translate linearly to another.
La evidencia humana hasta hoy
Two independent human cohorts have tested that hypothesis with big data:
- Brito J.P., Pisaniello F. and collaborators published in in 2025 a multinational cohort from 6 countries, comparing 98,147 GLP-1 users with 2,488,303 DPP-4 users. No significant difference in risk of thyroid cancer.
- Wang L. and collaborators in 2024, in the already mentioned TriNetX cohort of 1,651,452 patients: HR 0.99 (95% CI 0.79–1.24) for thyroid cancer. Neither increase nor reduction.
What DOES remain:
What the Study DOESN'T Say
It is necessary to be precise about the limits of this evidence. Three important caveats:
- It is observational evidence, not causal:
- Applies to people with type 2 diabetes:
- There is a discordant meta-analysis:BMC Gastroenterology
Conclusion: an Open Question with a Good Slope
Evidence through 2026 suggests that GLP-1 receptor agonists — semaglutide, tirzepatide, liraglutide, and others — are associated with lower risk of obesity-related cancers in people with type 2 diabetes. The signal is robust in magnitude, consistent across independent cohorts, and biologically plausible. Thyroid controversy has not been confirmed in humans at a population level, although specific contraindications (familial MTC, MEN2) remain in place with good reason.
Still, several important boundaries must remain clear. The evidence is observational, GLP-1 does not seem to provide additional benefit compared to metformin on shared metabolic pathways, and the evidence in people without diabetes is not yet closed.
For now, the most honest thing is this: a class of drugs that was developed to improve glycemic control appears to reduce, as a side effect, the risk of several cancers associated with impaired metabolism. If this observation is confirmed in prospective trials, GLP-1 will be among the metabolic therapies with the greatest comprehensive impact on public health of the century.
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Semaglutida Tirzepatida RetatrutidaReferencias Clave
- Wang L., Xu R., Kaelber D.C., Berger N.A. Glucagon-like Peptide 1 Receptor Agonists and 13 Obesity-Associated Cancers in Patients With Type 2 Diabetes. JAMA Network Open 2024;7(7):e2421305. [Link]
- Wang L., Berger N.A., Kaelber D.C., Xu R. Association of GLP-1 Receptor Agonists and Hepatocellular Carcinoma Incidence and Hepatic Decompensation in Patients With Type 2 Diabetes. Gastroenterology 2024;167:689–703. [Link]
- Tangella A.V. et al. GLP-1 receptor agonists and pancreatic cancer risk: a meta-analysis of real-world and trial evidence. Journal of Clinical Oncology 2026;44(2 suppl):712.
- Bjerre Knudsen L. et al. Glucagon-like peptide-1 receptor agonists activate rodent thyroid C-cells causing calcitonin release and C-cell proliferation. Toxicologic Pathology 2013;41(2):303–309. [Link]
- Brito J.P., Pisaniello F. et al. GLP-1 Receptor Agonists and Thyroid Cancer: A Multinational Cohort Study. Thyroid 2025.
- Wong C.K., McLean B.A., Baggio L.L., Drucker D.J. et al. Central GLP-1 receptor activation mediates the systemic anti-inflammatory effect of GLP-1 receptor agonists. Cell Metabolism 2024;36(1):130–143. [Link]
- Cencioni C. et al. Semaglutide remodels pancreatic cancer-associated fibroblasts in preclinical models. Journal of Experimental & Clinical Cancer Research 2025;44(1):18. [Link]
- Wen et al. Evaluating the Rates of Pancreatitis and Pancreatic Cancer Among GLP-1 Receptor Agonists. Endocrinology Diabetes & Metabolism 2025.
