New Orleans cancer specialists are watching a new set of data closely, as it hints that the wildly popular class of diabetes and weight-loss medications known as GLP-1 receptor agonists might be tied to lower rates of colon cancer. A large retrospective study found that people taking GLP-1s had about a one-third lower observed incidence of colorectal cancer than people on aspirin. Researchers are quick to stress that this is correlation rather than proof that the drugs actually prevent cancer, and local oncologists say the findings are encouraging but not strong enough to change prevention guidelines yet, as per ASCO.
Study flags lower colorectal cancer rates in GLP-1 users
The analysis was presented at the American Society of Clinical Oncology's Gastrointestinal Cancers Symposium and showed roughly a 36% lower incidence of colorectal cancer among GLP-1 users compared with aspirin users, according to ASCO. The difference held steady across age groups and body-mass index categories and remained consistent in multiple sensitivity analyses.
How researchers stacked GLP-1s up against aspirin
To make the comparison, investigators pulled from de-identified electronic health records and used propensity-score matching to build two similar groups. They matched about 140,828 people taking GLP-1s with an equal number taking aspirin, for a total of roughly 281,656 patients, and followed their outcomes over several years, UT Health San Antonio reports. This kind of design helps even out known differences between the two groups, but it cannot get rid of hidden or unmeasured biases that come with observational research.
Local lens: Ochsner oncologist sees promise, urges caution
Dr. Jonathan Mizrahi, a gastrointestinal medical oncologist at Ochsner MD Anderson Cancer Center in New Orleans, told NOLA that the GLP-1 signal “looks promising relative to aspirin.” He also disclosed that he uses GLP-1 therapy himself and said the findings make him more comfortable recommending it to some patients. Even so, he underscored that an association is not proof of causation and called for larger, prospective trials before anyone treats GLP-1s as a colon cancer preventive.
Aspirin's long, complicated history in cancer prevention
Aspirin has been in the colorectal cancer prevention conversation for decades. Pooled analyses suggest that long-term use, typically five years or more, can reduce colorectal cancer incidence by about 20 to 30%, but that potential benefit comes with a higher risk of serious bleeding, according to a review in the Journal of the National Cancer Institute. That tradeoff is why public-health recommendations treat aspirin chemoprevention with caution instead of embracing it across the board.
Possible reasons for the GLP-1 signal, and the big “but”
Study authors and commentators have floated several biologically plausible reasons GLP-1s might be linked to a lower colorectal cancer risk. The list includes reduced inflammation, better insulin sensitivity and weight loss, along with direct GLP-1 receptor activity in the colon that could influence the microbiome or interfere with tumor growth pathways, according to a summary in Cancer Discovery. They also repeatedly stress that the current data are observational, not proof, and say randomized trials or other prospective studies are needed to show whether the relationship is truly causal.
What patients should take away right now
Clinicians and the study team alike say patients should not start or stop any medication based on this single analysis. The absolute difference in risk is small, and the number needed to treat is large: on the order of two thousand people would have to be treated to prevent one case of colorectal cancer in the short term, according to coverage of the ASCO presentation by Drugs.com. For now, the standing advice is to talk with your doctor about screening and proven prevention strategies, rather than changing medications based on early observational hints.
