GLP-1 Drugs May Improve Breast Cancer Outcomes, Three Studies Suggest

The possible benefits associated with GLP-1 drugs, including Ozempic and Wegovy, continue to grow.

Initially developed to manage diabetes, these newer medicines are now used as injections by millions of additional people seeking to lose weight.

Yet their advantages could reach well beyond metabolic health.

As GLP-1 medicines such as semaglutide and liraglutide become increasingly popular, researchers have identified a notable trend: people using them appear to experience lower rates of illnesses including brain, kidney, heart and liver disease, as well as cancer.

GLP-1 drugs and breast cancer risk

Three new observational studies now indicate that GLP-1 drugs may offer particular benefits in relation to breast cancer.

Their findings indicate that people taking GLP-1 medicines have 30 percent lower odds of developing breast cancer. Among those diagnosed, they are also half as likely to have their breast cancer spread and 6 percent less likely to die from the condition.

These encouraging findings were presented before publication at the American Society of Clinical Oncology (ASCO) annual meeting in Chicago.

Elizabeth McDonald, a practising breast radiologist at the University of Pennsylvania, presented the first study.

Her team assessed health records from more than 110,000 women aged between 45 and 80 who had a BMI of 25 or above, the threshold considered "overweight".

Of the women recruited from 2022 to 2025, almost 14 percent had recorded prescriptions for GLP-1 medication.

Although the research did not consider the length of time participants had used GLP-1 drugs, it found that women who had ever taken them were 30.5 percent less likely to receive a breast cancer diagnosis.

That association remained after the researchers accounted for age, race, ethnicity, BMI, breast density and diabetes status.

"Our study was observational and does not definitively confirm an association between GLP-1 medications and reduced breast cancer incidence," explains McDonald.

"It does add to the growing body of evidence suggesting that it's worth investigating these weight loss drugs as potential cancer prevention tools."

McDonald and her colleagues are currently developing a clinical trial to examine whether these medicines can reduce breast cancer incidence among women at high risk.

"GLP-1 medications are intriguing from a cancer research perspective because they weren't designed for cancer therapy, but they do affect many different targets and pathways associated with cancer development, so we're eager to study them in this context," says McDonald.

Breast cancer progression and survival findings

A separate study presented at the same conference likewise supports further research into GLP-1 drugs and breast cancer.

Among more than 12,000 people with lung, breast, colorectal or liver cancer, participants using GLP-1 drugs in the analysis had a significantly lower risk of their cancer spreading than people using another diabetes medicine.

For breast cancer specifically, 10 percent of patients taking GLP-1 drugs progressed to a more advanced stage, compared with 20 percent of those taking another diabetes drug.

"Our study found that use of GLP-1 drugs… was associated with a meaningful reduction in cancer progression across 4 solid tumor types," says lead study author Mark David Orland, an oncologist from the Taussig Cancer Institute at Cleveland Clinic.

"It provides early evidence that future studies are worth pursuing."

The third breast cancer study presented at ASCO's annual meeting adds further weight to this line of research.

It reported that, among 137,493 breast cancer patients, people treated with GLP-1 drugs continuously for at least three months had a 6 percent higher overall survival rate after five years.

The authors said further research is needed to establish whether a biological mechanism explains this association.

How GLP-1 drugs may affect cancer

GLP-1 drugs are intended to imitate naturally occurring hormones that reduce appetite and encourage weight loss. However, emerging evidence indicates that this may be only one aspect of their effects. The medicines also appear to influence inflammation and immune function.

Obesity is associated with poorer outcomes for breast cancer patients, but weight reduction might not be the sole reason GLP-1 drugs could lower risk.

"GLP-1 receptor agonists have never been just glucose-lowering drugs," says Marcin Chwistek, an oncologist at Fox Chase Cancer Center and an ASCO Expert in supportive care.

"Their anti-inflammatory and immune-modulatory properties have long suggested broader effects. What's new here is the consistency across tumor types, and data this large and this consistent warrant a prospective randomized trial."

Estimates for this year suggest that more than 320,000 women in the US will be diagnosed with breast cancer, while around 40,000 will die from it.

With any luck, a medicine capable of improving those figures may already be available.

All three sets of findings were shared at the American Society of Clinical Oncology's annual meeting in Chicago.