Oncology already accounts for nearly 37% of all pharmaceutical R&D spending. Now, pharmaceutical companies are pouring billions into validating the link between weight-loss drugs like GLP-1 medications and cancer cure. Driven by this, the global GLP-1 market is projected to exceed $100 billion by 2030.
A growing share of this investment is now funding dozens of clinical trials testing whether these metabolic drugs can also fight tumors.
Findings from these trials show that GLP-1 drugs lower the risk of developing 13 cancer types strongly associated with obesity.
In some cases, like breast, colorectal, and liver cancers, these medicines even reduce the chances of developing tumors by 30–40% over long-term use.
These drugs also slow tumour growth, and even restore the effectiveness of some treatments when tumours become resistant.
For instance, in liver cancer, which no longer responds to lenvatinib, adding semaglutide helped restore sensitivity. It made tumours shrink again without adding more targeted drugs.
Similar approaches with GLP-1 drugs are now being explored with other cancer treatments, such as Tyrosine Kinase Inhibitors (TKIs), immune therapies, and standard chemotherapy.
How different tumours behave differently to GLP-1
Not all cancers respond the same way. Higher levels of the GLP-1 receptor are linked with better survival in several cancers, including bladder, breast, kidney, thyroid, and esophageal adenocarcinoma. These may be strong candidates for early clinical testing.
But in cervical, lung squamous, stomach, and uterine endometrial cancers, higher receptor levels are tied to worse outcomes, raising concerns that GLP-1 drugs might unintentionally support tumour growth.
In a study of 357 neuroendocrine tumors, lab staining showed that GLP-1 receptors were present in 45% of duodenal, 17% of gastric, and 14% of pancreatic tumors.
When patient-derived tumor spheroids were exposed to semaglutide, they grew 1.4- to 2-times faster, indicating a potential cancer-promoting risk in these tumor types.
For colon, pancreatic, and esophageal squamous cancers, the impact is still unclear.
GLP-1 can improve survival chances and life expectancy for Non-Small Cell Lung Cancer (NSCLC) patients
In lung cancer, GLP-1 drugs have shown the strongest signs of benefit so far. In a study of 1,177 people with diabetes and non–small cell lung cancer, those using GLP-1 medicines stayed cancer-free for a significantly longer period after surgery.
An analysis of 300 patients with advanced NSCLC found that the 10 individuals taking GLP-1 drugs alongside immunotherapy lived longer and kept their cancer under control for longer.
In pre-clinical studies, combining liraglutide, a GLP-1 drug, with anti-PD-1 immunotherapy completely eliminated tumors in mice with Lewis lung cancer. The treatment also provided the immune cells’ memory to attack the tumor quickly if it returns.
Prostate cancer has the strongest, clearly measurable decrease in GLP-1 users
GLP-1 drugs offer a two-fold benefit for men at risk of prostate cancer. They improve blood sugar control and reduce heart-related risks, both important factors linked to prostate cancer outcomes. Because of this overlap, experts are encouraging short pre-surgery “window-of-opportunity” trials to better understand how GLP-1 drugs might help in real-world prostate cancer treatment.
In the LEADER cardiovascular trial, diabetic men taking liraglutide had a 46% lower chance of developing prostate cancer compared with those on a placebo.
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Endometrial cancer research shows the strongest lab and molecular evidence with GLP-1 drugs
Studies done on Endometrial tumors taken out from patients show very low levels of the GLP-1 receptor. The cancer has inherently “switched off” the GLP-1 receptor.
When researchers artificially increased GLP-1 receptor levels in endometrial cancer cells, they underwent apoptosis (self-destruction of abnormal cells). These cancer cells stopped growing, invading, or migrating. Mouse xenograft models showed the same tumor-suppressing effects.
These results make Endometrial cancer a high-priority target for moving GLP-1 therapies into clinical trials more quickly.
GLP-1 has strong immune and biological links to colon cancer
Colorectal tumors (CRC) show much lower activity of key GLP-1 signalling genes, such as ITPR1 and ADCY5, compared with healthy tissue from the same patients.
Lab studies show that semaglutide directly slows the movement of colorectal cancer cells, with stronger effects at higher doses.
When GLP-1 drugs are combined with checkpoint blockade immunotherapies (e.g., anti-PD-1, anti-CTLA-4), tumors become more responsive. This approach may be especially effective in MSI-high or highly mutated colorectal cancers, which are already more sensitive to immune-based treatments.
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Strong pre-clinical data supporting GLP-1 therapy in liver cancer or Hepatocellular Carcinoma (HCC)
Liver cells (hepatocytes) carry GLP-1 receptors, which means GLP-1 drugs can act directly on the liver.
Animal studies show that GLP-1 drugs can influence several liver cancer-related pathways. It can help reduce inflammation, slow tumor growth, and control oxidative stress. When combined with immunotherapy, this approach led to complete tumor regression in animal models.
In people with cirrhosis, doctors need to weigh the benefits and risks of GLP-1 drugs carefully. The weight loss they cause could worsen cachexia, a serious muscle-wasting condition common in advanced liver disease.
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Safety considerations for using GLP-1 in cancer treatment
To move forward, researchers need randomized controlled trials to determine the optimal anticancer dose and dosing schedule for GLP-1 drugs. This may require higher levels of GLP-1 drug doses than those used for metabolic diseases. These trials should also confirm whether GLP-1 receptor levels can predict response, assess long-term safety in non-diabetic cancer patients, and uncover how tumors might develop resistance to this treatment.
Some neuroendocrine tumours carry GLP-1 receptors, and lab studies show that semaglutide can speed up growth in patient-derived samples. This suggests a real risk in these cancers and signals the need to widen current safety warnings.
For instance, the existing safety warnings for patients with medullary thyroid cancer or MEN2 may need to be expanded to include additional risk groups.
Because GLP-1 drugs can sharply reduce appetite, they may worsen muscle wasting in vulnerable patients. Future trials should track changes in body composition rather than just overall weight loss.
What’s Next for GLP-1 in Cancer Treatment
Using GLP-1 drugs before surgery or systemic therapy could act as a form of metabolic priming. It can lower insulin and IGF-1 levels, weakening the tumor and reducing its size before treatment.
To improve future treatment outcomes, selecting patients based on GLP-1 receptor levels or metabolic profiles is essential. It will help identify those most likely to respond to GLP-1 therapies.
Once safe dosing is confirmed, GLP-1 drugs could be used either sequentially or in combination with immunotherapies, chemotherapy, or tyrosine kinase inhibitors to create more effective treatment regimens.
What Still Needs to Be Answered
GLP-1 receptor agonists are showing promise as add-on treatments across several cancer types. This promise is supported by a range of evidence, from retrospective patient studies to detailed lab and animal research that explains their underlying mechanisms.
Keeping an eye out for emerging research and evidence is important for researchers, clinicians, and pharma development teams to launch specific treatments early and gain a competitive advantage in the GLP-1 landscape.
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