GLP-1 drugs may improve cancer treatment outcomes, study suggests

SEOUL (Yonhap) -- Four new studies have recently suggested that GLP-1 class drugs for obesity and diabetes, such as Wegovy and Mounjaro, may improve treatment outcomes for cancer patients, the U.S. daily Wall Street Journal (WSJ) reported on the 21st (local time).

A study led by researchers at the Cleveland Clinic Cancer Institute tracked more than 10,000 patients diagnosed with early-stage cancer who started taking GLP-1 drugs, comparing disease progression with patients who took other diabetes treatments.

The results showed a lower probability of cancer metastasis in the GLP-1 taking group.

Specifically for lung cancer patients, the rate of progression to advanced disease (where the disease has spread beyond the initial stage to surrounding tissues or other organs) was less than half in the GLP-1 taking group (10%) compared to the control group (22%).

A similar pattern was observed in breast cancer patients, with 10% in the GLP-1 group versus 20% in the control group, and statistically significant reductions were also seen in colorectal and liver cancers.

Mark Olland, a resident physician at Cleveland Clinic, pointed out that millions of Americans are taking GLP-1, emphasizing, "It is clearly very important that we immediately understand what the potential anti-tumor effects are."

He is scheduled to present the research at the American Society of Clinical Oncology (ASCO) 2026 Annual Meeting, to be held in Chicago from the 29th of this month to the 2nd of next month.

There are also studies examining whether GLP-1 users have a lower probability of developing breast cancer and if their survival period is longer after diagnosis.

According to a paper analyzing over 137,000 breast cancer patients from the University of Texas MD Anderson Cancer Center, the 5-year survival rate for GLP-1 drug users was over 95%, higher than for non-users (89.5%).

Dr. Jasmine Sukumar, a breast oncologist at MD Anderson Cancer Center who participated in this study, stated that this trend is visible across various databases, adding, "It is certainly interesting because all these studies have slightly different designs."

A study by the University of Pennsylvania, which examined about 95,000 women who underwent breast imaging, found that women who took GLP-1 drugs had about a 25% lower probability of being diagnosed with breast cancer, even after accounting for other risk factors such as age and weight.

The reasons why GLP-1 drugs appear to be effective against cancer are still unclear, and there are several hypotheses.

Some suggest that they indirectly lower the risk of cancer by promoting weight loss and improving metabolic health. Others point to the expression of GLP-1 receptors on the surface of some cancer cells, suggesting the drugs may act more directly on the biological mechanisms of cancer.

GLP-1 drugs have already been approved for reducing the risk of heart attack and stroke, in addition to lowering blood sugar and promoting weight loss.

Clinical trials are also underway to test their efficacy in alleviating sleep apnea and suppressing addictive behaviors.

The four recently published studies suggest that, in addition to these benefits, they may also have anti-cancer effects.

However, these studies are not meticulously designed clinical trials to verify efficacy as a treatment, but rather observational studies through retrospective reviews. They only show correlation, not causation.

The patients in the studies were already taking the drugs for diabetes or obesity, and the researchers analyzed their medical records to find statistically significant trends. It is pointed out that further research is needed to confirm implications such as the possibility of anti-cancer effects.

In particular, patients prescribed GLP-1 drugs tend to have better access to medical services and more consistent follow-up care than patients who do not, and it is suggested that these non-clinical advantages may independently improve patient prognosis.

Therefore, to rigorously verify whether there are anti-cancer effects, randomized controlled clinical trials that thoroughly control for differences in income level, background health, and medical accessibility are essential.

Nevertheless, Jaroslaw Maciejewski, associate director of the Cleveland Clinic Cancer Institute, noted the consistent results across data from hundreds of thousands of individuals, saying, "It is difficult to ignore these numbers."

Eli Lilly, the manufacturer of Mounjaro, and Novo Nordisk, the manufacturer of Wegovy, are not currently researching the anti-cancer effects of these drugs.