GLP-1 medications such as Ozempic and Wegovy may help lower the risk of certain cancers, a new study suggests.

People who are overweight or obese have a higher risk of getting 13 types of cancer, and the risk increases the longer a person is overweight and the more excess weight they gain. About 40 per cent of new cancer diagnoses are associated with excess weight, according to the U.S. Centers for Disease Control and Prevention. In 2021, there were about 170 new diagnoses for every 100,000 people, CDC data shows.

But a study published Friday in the journal JAMA Network Open found that people with type 2 diabetes who were being treated with a class of GLP-1 drugs were significantly less likely to be diagnosed with 10 of the 13 obesity-associated cancers than those who were taking insulin.

The risk was cut by more than half for gallbladder cancer, meningioma, pancreatic cancer and hepatocellular carcinoma, a kind of liver cancer. It was also significantly reduced for ovarian cancer, colorectal cancer, multiple myeloma, esophageal cancer, endometrial cancer and kidney cancer.

Excess weight can cause changes in the body such as long-lasting inflammation and higher than normal levels of insulin, insulin-like growth factor and sex hormones that can cause cancer, according to the CDC. And GLP-1 medications interact with systems related to insulin production.

The new findings that link GLP-1 treatment to reduced risk of some cancers “compare favourably” with similar effects linked to intensive lifestyle intervention and metabolic-bariatric surgery that have been found in other trials, the study authors wrote.

However, the research found that GLP-1 treatment was not associated with a reduced risk of postmenopausal breast cancer, which CDC data shows is the most common type of cancer associated with obesity.

Risk was also not reduced for stomach cancer or thyroid cancer. In fact, other research has found that GLP-1s may interact with the body’s insulin production in ways that negatively affect the thyroid, and the study authors note that patients should be aware of potential thyroid-related risks that are included on the medication’s packaging.

The new study also found that the risk of cancer diagnosis for people with type 2 diabetes was not different among those who were treated with GLP-1s compared with those where were being treated with metformin. In fact, the risk of diagnosis with kidney cancer was higher among those using GLP-1s than those on metformin.

For this study, researchers from the Case Western Reserve University School of Medicine and the MetroHealth System analyzed more than a decade of medical records for nearly 1.7 million people with type 2 diabetes.

More information is needed about how reduced cancer risk may relate to the scale of weight loss, but the findings provide “preliminary evidence of the potential benefit of GLP-1RAs for cancer prevention in high-risk populations and support further preclinical and clinical studies,” the study authors wrote.