As GLP-1 medications reshape treatment for obesity and diabetes, researchers are examining whether the drugs could also affect cancer risk, recurrence and survival. The possibility has generated significant interest, but major questions remain unanswered.

The American Association for Cancer Research’s 2026 Cancer Progress Report, released earlier this month, identified obesity as a major risk factor for many cancers. The report discussed glucagon-like peptide-1 medications, including semaglutides such as Ozempic and Wegovy and tirzepatides such as Mounjaro and Zepbound.

These medications can produce substantial weight loss and improve metabolic health. Although the report cited studies suggesting that GLP-1 drugs may reduce the risk of certain cancers, it stressed that the evidence remains mixed.

“Randomized clinical trials remain the gold standard ... however, such trials have not yet been conducted specifically to assess cancer outcomes associated with GLP-1 RA use,” the report stated.

Sai Yendamuri, M.D., a thoracic surgeon at Roswell Park Comprehensive Cancer Center in Buffalo, New York, said obesity is a leading cause of cancer, second to smoking. He also identified alcohol and poor nutrition as risk factors “which are all layered into obesity.”

“So if obesity is related to cancer – both in terms of causing it and increasing its progression – the logical question is, would a drug that decreases obesity have an impact?” Yendamuri told Fox News Digital. He was not associated with the AACR report.

Yendamuri said several lines of evidence point toward a potential benefit. “For example, when people studied patients who were having metabolic surgery to decrease obesity, for example, the incidence of cancer decreased in those patients.”

Researchers have also compared cancer incidence among patients taking GLP-1 receptor agonists with incidence among patients who were not using the medications. Many of those studies associated the drugs with lower cancer risk and higher survival, according to Yendamuri.

“And then they compared the incidence of cancer in those patients to patients who were not taking GLP-1 receptor agonists – and many of those studies found that the risk of cancer was lower and the survival was higher in the patients taking GLP-1s,” he said.

Most studies showed that pattern, but some found no relationship, Yendamuri noted. A couple of studies found an increased risk of certain cancers, including thyroid cancer.

“The reason you find this disconnect … is because these are retrospective studies,” he said. “That is, they look at existing data, and they're trying to derive associations from existing data … but there are many other variables that can impact the result.”

Yendamuri and his research team have conducted studies into obesity and lung cancer. “We have found in every investigation we've done that obesity does increase the risk of lung cancer,” he said.

How obesity is defined and measured can also affect research, according to Yendamuri. While body mass index has traditionally served as the standard measurement, many researchers are moving away from relying on BMI alone and are using more precise assessments of body fat composition.

Yendamuri described two findings from his research involving GLP-1 medications and cancer outcomes. “If someone's having a resection, a lung cancer surgery, for patients who are on GLP-1 receptor agonists, the recurrence rate seems to be lower.”

He also said patients with advanced cancers who were receiving immunotherapy and taking GLP-1 drugs had lower recurrence rates. Based on preclinical laboratory studies, however, Yendamuri believes the medications have only a limited direct effect on cancer cells.

“What we think is happening is that it changes the body’s immune response to cancer cells, and thereby improves its ability to fight cancer cells,” he told Fox News Digital. The effect could vary by cancer type because immune responses are more important in some cancers than in others.

“For example, in some cancers like melanoma, we know that the immune response is incredibly important,” Yendamuri said. He acknowledged that at least part of any cancer benefit from GLP-1 medications probably comes from weight loss.

“Not every patient who takes GLP-1 receptor agonists responds with a substantial weight loss, so in future trials, it would be interesting to see if the benefit for patients depends on the weight loss,” he said. Comparing patients who lose weight with those who do not could help answer that question.

Depending on future trial results, Yendamuri is hopeful that GLP-1 drugs might eventually be viewed as a preventive mechanism for cancer. He also emphasized continued funding for the National Cancer Institute, which supports researchers seeking to advance cancer research and develop new discoveries.