A new study suggests women with type 2 diabetes who used GLP-1 receptor agonists after a breast cancer diagnosis had better overall survival than non-users. Learn what the findings mean, their limitations, and why more research is needed.
- Women with type 2 diabetes who used GLP-1 drugs after breast cancer diagnosis had a lower risk of death during follow-up
- Researchers observed nearly a 49% lower risk of overall mortality among GLP-1 users compared with non-users
- The study was observational and did not prove that GLP-1 drugs directly improve breast cancer survival
GLP-1 receptor agonists have transformed the treatment of type 2 diabetes and obesity by helping lower blood sugar levels and promoting weight loss. More recently, researchers have begun investigating whether these medicines may also influence cancer outcomes (1✔ ✔Trusted Source
GLP-1 receptor agonist use and overall survival among women with type 2 diabetes and breast cancer: a retrospective cohort study
).
A new retrospective study suggests that women with type 2 diabetes who used GLP-1 receptor agonists after being diagnosed with breast cancer had better overall survival than similar patients who did not receive these medications. While the findings are encouraging, researchers caution that the study shows an association rather than a cause-and-effect relationship.
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How Does Type 2 Diabetes Affect Breast Cancer Outcomes?
Type 2 diabetes is associated with chronic inflammation, insulin resistance, and elevated insulin levels, all of which have been linked to poorer outcomes in several cancers, including breast cancer.
Because GLP-1 receptor agonists improve blood sugar control and often lead to weight loss, scientists have questioned whether these medications might also improve long-term outcomes in people living with both diabetes and cancer.
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How Did Researchers Study This?
Researchers from City of Hope conducted a single-centre retrospective cohort study involving women with type 2 diabetes who were diagnosed with breast cancer between 2009 and 2025.
To reduce differences between treatment groups, investigators used propensity score matching, creating 226 matched pairs of patients based on their clinical characteristics.
Women were then grouped according to whether they received a GLP-1 receptor agonist after their breast cancer diagnosis. Researchers compared overall survival using multivariable statistical analyses and Kaplan-Meier survival curves.
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GLP-1 Users Had a Lower Risk of Death
During the follow-up period, researchers recorded 47 deaths:
|
Group |
Deaths |
|
No GLP-1 therapy |
30 |
|
GLP-1 therapy |
17 |
After adjusting for multiple clinical factors, women who received GLP-1 receptor agonists had a 49% lower risk of overall death compared with those who did not use these medications.
Key Findings
|
Outcome |
Result |
|
Study design |
Retrospective propensity score-matched cohort |
|
Matched participants |
226 pairs |
|
Overall mortality |
Lower among GLP-1 users |
|
Hazard ratio |
0.51 |
|
95% Confidence Interval |
0.28–0.93 |
|
Statistical significance |
p=0.03 |
Among women with stage I to III breast cancer, the association remained similar, with an estimated 55% lower overall mortality risk (hazard ratio 0.45). Kaplan-Meier analysis also showed improved overall survival among GLP-1 users.
Why Could GLP-1 Drugs Affect Cancer Outcomes?
Researchers have not yet established exactly why GLP-1 receptor agonists might be linked to improved survival.
Several possible explanations include:
- Better blood sugar control
- Weight reduction
- Lower insulin levels
- Reduced chronic inflammation
- Improved cardiovascular and metabolic health
These benefits may improve a patient’s overall health during and after cancer treatment. However, the current study did not investigate the biological mechanisms responsible for the observed association.
What the GLP-1 Breast Cancer Study Shows, and What It Doesn’t
Although the findings are promising, they should be interpreted carefully.
What the Study Suggests
|
Study Findings |
Current Limitations |
|
GLP-1 use was associated with better overall survival. |
The study was observational and cannot prove causation. |
|
Similar results were seen in women with stage I–III breast cancer. |
Researchers measured all-cause mortality, not breast cancer-specific deaths. |
|
GLP-1 therapy may have benefits beyond diabetes management. |
The study included only women with type 2 diabetes and breast cancer, so results may not apply to other groups. |
Researchers emphasised that additional prospective studies and clinical trials are needed before GLP-1 receptor agonists can be considered part of routine breast cancer treatment.
Should People with Breast Cancer Start GLP-1 Drugs?
Not based on this study alone.
GLP-1 receptor agonists are currently approved for treating type 2 diabetes and, in some cases, obesity. They are not approved as cancer treatments.
People with breast cancer should continue following their oncologist’s treatment recommendations. If they also have diabetes, decisions about GLP-1 therapy should be made in consultation with both their oncologist and diabetes specialist.
A Growing Area of Cancer Research
Scientists are increasingly exploring how medications developed for metabolic diseases may influence cancer outcomes.
As obesity and diabetes become more common worldwide, understanding whether therapies such as GLP-1 receptor agonists can improve survival or treatment response could help shape future cancer care.
Larger studies will be needed to determine whether the observed benefits reflect the drugs themselves or improvements in overall metabolic health.
Frequently Asked Questions
Q: What are GLP-1 receptor agonists?
A: GLP-1 receptor agonists are medicines used to treat type 2 diabetes and obesity. They help lower blood sugar, reduce appetite, and promote weight loss.
Q: Did this study show that GLP-1 drugs treat breast cancer?
A: No. The study found an association between GLP-1 use and better overall survival, but it did not show that these medicines directly treat breast cancer.
Q: Does this benefit apply to everyone with breast cancer?
A: No. The study included only women with type 2 diabetes who developed breast cancer. The findings cannot be generalised to patients without diabetes.
Q: Did the study measure breast cancer deaths?
A: No. Researchers measured overall (all-cause) mortality, which includes deaths from any cause, not just breast cancer.
Q: Should people with breast cancer ask for GLP-1 drugs?
A: Patients should not start GLP-1 medications solely to improve cancer outcomes. Treatment decisions should be based on approved indications and discussed with their healthcare team.
Reference:
- GLP-1 receptor agonist use and overall survival among women with type 2 diabetes and breast cancer: a retrospective cohort study – (https://academic.oup.com/oncolo/article/31/8/oyag268/8732540)
Source-Medindia