- In 2022, about 2.5 billion adults globally were living with obesity.
- Past studies show that obesity can increase a person’s risk for a number of cancers.
- A new study provides evidence suggesting that GLP-1 medications for weight loss likely have little to no impact on a person’s obesity-related cancer risk.
Researchers estimate that, in 2022, about
Obesity-related cancers include thyroid, pancreatic, breast, kidney, colorectal,
For this study, researchers analyzed findings from 48 previously-conducted trials examining the safety and efficacy of GLP-1 drugs on people with type 2 diabetes, overweight, or obesity, involving a total of more than 94,000 participants.
“GLP-1 receptor agonists are now being used by millions of people worldwide for diabetes and obesity, yet their long-term cancer safety has remained uncertain,” Cho-Han Chiang, MD, MMSc, clinician investigator in the Department of Medicine in Mount Auburn Hospital at Harvard Medical School in Massachusetts, and corresponding author of this study, told Medical News Today.
“Early observational studies and case reports raised concerns about potential links with certain cancers (e.g. thyroid, pancreatic cancers),” Chiang noted.
“At the same time, other observational studies have suggested a lower risk of certain cancers, particularly obesity-related cancers, with GLP-1RA use,” he added. “This mixture of signals has contributed to uncertainty in the field and the need to investigate further.”
Chiang said they chose to specifically study obesity-related cancers because these cancers are strongly influenced by excess adiposity, chronic inflammation, and metabolic dysregulation.
“Obesity increases the risk of these malignancies — there are 13 types of cancer recognized as associated with obesity — and GLP-1 receptor agonists produce meaningful and sustained weight loss,” he continued.
“This raises the question of whether GLP-1RAs could reduce the risk of obesity-related cancers. Recent
“However, these are data from non-randomized studies with [the] possibility of confounding factors at play,” Chiang noted.
“Our study pulls together cancer events across large randomized clinical trials to provide a more rigorous and comprehensive assessment of cancer risk with GLP-1RAs,“ he told us. “It helps fill a critical gap for clinicians, regulators, and patients who must balance substantial metabolic and cardiovascular benefits against theoretical long-term cancer risks.”
At the study’s conclusion, researchers determined that GLP-1 drugs probably had little to no impact on the risk for thyroid, pancreatic, breast, or kidney cancers.
“The significance of this finding is that it directly addresses several long-standing safety concerns,” Chiang said.
“For example, thyroid cancer and pancreatic cancer have been mentioned prior as potential areas of risk for GLP-1 receptor agonists. However, much of that concern came from small signals, preclinical studies, or observational data that were prone to confounding,” he noted.
“At the same time, it is important to emphasize that trial follow-up is still relatively short for cancers that develop over many years,” Chiang continued.
“Our results suggest that current GLP-1RA use does not appear to meaningfully increase short- to intermediate-term risk, but they do not rule out the possibility of effects, harmful or beneficial, over longer durations. Continued long-term surveillance will be essential.”
– Cho-Han Chiang, MD, MMSc
Chiang and his team also concluded that the evidence was of low certainty for colorectal, esophageal, and liver cancers risk, and that the impact of GLP-1 drugs on gastric cancer risk was very uncertain.
“The significance of these findings is that they highlight areas where current evidence is simply too limited to draw firm conclusions, even across large randomized trials,” Chiang explained. “For colorectal, esophageal, liver, and gastric cancer, the number of events in trials was very small, and follow-up durations were relatively short.”
As this study shows that GLP-1 medications probably have little or no effect on obesity-related cancer risk, MNT asked Chiang if it is possible that these drugs may offer a protective effect against these cancers.
“Based on our analysis of randomized trials, GLP-1 medications probably have little or no effect on obesity-related cancer risk within the follow-up periods studied,” he responded. “However, this does not rule out the possibility of a protective effect over longer durations. In fact, there are several reasons why a protective effect has been hypothesized.”
“First, obesity is a major driver of several cancers through chronic inflammation, insulin resistance, and hormonal and metabolic pathways,” Chiang detailed.
“GLP-1 receptor agonists produce substantial weight loss and improve metabolic health, which could theoretically reduce the incidence of obesity-related cancers over time. Second, several recent observational studies have reported lower rates of certain cancers among GLP-1RA users,” he explained.
“Because randomized trials to date have relatively short follow-up and few cancer events, they may not yet capture long-term or delayed protective effects,” Chiang continued.
“From the perspective of current evidence, our study suggests that a clear protective effect has not yet been demonstrated in randomized data, but the possibility remains biologically plausible and supported by some real-world signals,” said the researcher.
MNT had the opportunity to speak with Anton Bilchik, MD, PhD, surgical oncologist, chief of medicine, and director of the Gastrointestinal and Hepatobiliary Program at Providence Saint John’s Cancer Institute in Santa Monica, CA, about this study.
His first reaction to the findings is that it needs a longer follow-up to come to the conclusion that GLP-1 drugs do not reduce the chances of getting obesity-related cancers, as the follow-up was only 1 to 2 years.
“The other issue with the study is that cancer was not a primary endpoint of the trials that they looked at […] so that in itself is certainly an issue in how this data is interpreted,” Bilchik continued.
“And finally, which I think is most important and a lot more research has to be done, is we do not know how long the people in these trials have been obese for. Suggesting that obesity-related cancers may start occurring earlier on, and then patients get these GLP-1 drugs that reduce weight, at which point the cancer cells have already started forming,” he told us.
“The GLP-1 drugs are truly the most exciting type of medication that has been approved in the last few years, given the massive epidemic of obesity and the relationship between obesity and cardiovascular disease … and other conditions such as cancer,” he added.
“Given the fact that we have this very effective way of treating what is an epidemic in this country, […] we need to know every possible aspect about these drugs, both the good and the bad,” noted Bilchik.
MNT also spoke with Mir Ali, MD, a board-certified general surgeon, bariatric surgeon, and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, about this research.
“As these [GLP-1] drugs are widely prescribed and there are still limitations on insurance coverage, finding more effects of these medications and long-term benefits may help make these drugs available to more people,” Ali commented.
“I would like to see if the degree of weight loss and the amount of time the weight is kept off affects cancer risk in obesity related cancers,” he told us.