GLP-1 Drugs May Lower Risk of 10 Obesity-Related Cancers, Study Shows

GLP-1 drugs may reduce the risk of certain obesity-associated cancers, according to a study published in JAMA Network Open last week.

In the study, scientists analyzed electronic health records of more than 1.6 million patients with type 2 diabetes who were prescribed a GLP-1 drug, insulin, or metformin between 2005 and 2018.

Compared to patients who took insulin, those prescribed GLP-1 drugs had a lower risk of developing 10 out of 13 cancers associated with obesity, including esophageal, colorectal, endometrial, gallbladder, kidney, liver, ovarian, and pancreatic, as well as meningioma and multiple myeloma.

“Our study provides crucial evidence that GLP-1RAs hold promise in breaking the link between obesity and cancer,” said Lindsey Wang, co-author of the study and a student in the BS-MD program at Case Western Reserve University.

“Most notably, we observed a significant risk reduction across multiple gastrointestinal cancers,” Wang told Verywell in an email. “This broad spectrum of effects is significant given the often poor prognosis associated with these cancers.”

The study also compared the diabetes medication metformin to GLP-1s. Patients who took metformin also had reduced risk for most cancer types, and they had an even lower risk of developing kidney cancer compared to the GLP-1 group.

The study adds to growing evidence that GLP-1 drugs, like Ozempic and Mounjaro, can provide health benefits beyond blood sugar control and weight loss for people with diabetes.

“Often, when we’re managing patients with diabetes, we talk to them about comorbidities like hypertension, hyperlipidemia, and cardiovascular risk. Cancer risk should be part and parcel of that,” Sonali Thosani, MD, an associate professor and Section Chief for diabetes at the University of Texas MD Anderson Cancer Center, who was not involved with the study, told Verywell. “Trying to prevent cancer in patients with diabetes by making sure they get age-appropriate screening, but also addressing their obesity, can really help reduce the risk of developing cancer.” 

What the Study Shows

Semaglutide, the active ingredient in Ozempic and Wegovy, was approved for type 2 diabetes in 2017 and for weight loss in 2021. The latest records analyzed in the study were from 2018, which means the patients may have been prescribed older GLP-1 medications, such as exenatide, liraglutide, or dulaglutide.

The study showed that the risk of several cancers—including hepatocellular carcinoma, gallbladder cancer, and pancreatic cancer—decreased by more than 50% in patients with diabetes taking a GLP-1 when compared to those on insulin. 

“I found it quite striking that this reduced cancer risk in patients on GLP-1 was similar to those treated with metformin, and that actually metformin conferred a greater beneficial effect on kidney cancer compared to GLP-1,” Bubu Banini, MD, PhD, an assistant professor of medicine specializing in digestive diseases at the Yale School of Medicine, told Verywell in an email.

Banini also found it “surprising” that people in this study who took a GLP-1 drug did not have a significantly lower risk of postmenopausal breast cancer, despite it being one of the most common types of obesity-associated cancers.

Not a Proof of Causality

The study was a retrospective cohort study, meaning scientists looked at preexisting health records to determine if there was a connection between diabetes treatment prescriptions and cancer diagnoses. However, it doesn’t prove the GLP-1 drug is the reason for lower cancer risks. Researchers will have to design randomized clinical trials to prove causality.

Thosani cautioned that health records can sometimes be incomplete or contain inaccuracies. Additionally, the study only tracked whether someone was prescribed a GLP-1 drug, but not whether they took it consistently or filled the prescription at all. The medications must be taken every week or every day, depending on the prescription, to be most effective.

“The patients that are represented in the study are those that had medical encounters. We may not be getting the full picture of patients who don’t have access to health care and may have increased risk of certain types of cancer,” Thosani said.

Why GLP-1s May Protect Against Cancer

Fat cells produce inflammatory markers, which can signal cells to multiply and grow uncontrollably, leading to DNA damage. GLP-1s likely reduce obesity-associated cancer risk because they are so effective at helping people lose fat, Thosani explained.

“When we reduce the adipose tissue, we’re reducing all of this inflammation and cell proliferation. Those factors help reduce the risk of cancer development,” Thosani said.

She added that metformin may be similarly effective at reducing cancer risk in diabetic patients because it can also cause weight loss. High levels of insulin can stimulate the growth of cancer cells. Taking metformin can reduce insulin resistance, thereby decreasing cancer risk.

While obesity is a key risk factor for all 13 of the cancers studied, it’s not the only risk factor, according to Banini.

In the case of prostate cancer, for instance, the GLP-1 drug could directly slow the development of cancer cells and allow the body to better destroy those cells, Banini said. The drugs could also make chemotherapy more effective for treating pancreatic cancer.

Newer GLP-1 medications like Zepbound (tirzepatide) may prove to be more cancer-protective because they tend to cause more weight loss and better glycemic control.

Some studies already consider whether there are factors beyond weight loss that cause GLP-1s to influence cancer outcomes for those with diabetes.

“It could be interesting to see what other factors are at play,” Thosani said. “Could this drug be helpful in patients who are at higher risk for certain cancers but do not have obesity?”