GLP-1 drugs appear to reduce cancer risk across multiple tumor types, but researchers say mechanism is still unclear

GLP-1 drugs — originally developed as diabetes treatments and now widely used for obesity and related conditions — were a major research theme at last month's American Society of Clinical Oncology (ASCO) meeting, where four studies examined their potential relationship to cancer risk. ASCO highlighted those studies, some of which were published in its affiliated Journal of Clinical Oncology.

The most prominent study reviewed medical and prescription records from more than 10,000 patients with early-stage cancer. It found that GLP-1 use was associated with reduced cancer risk in six of seven cancer types examined — with statistically significant reductions in breast, liver, colorectal, and non-small cell lung cancer. Kidney and prostate cancer risks declined somewhat, while pancreatic cancer was least affected. For non-small cell lung cancer specifically, NPR reported that the rate of progression to Stage IV disease was 22.3% among patients not taking a GLP-1, compared with 10% among those who were.

A separate analysis matched mammogram images to a prescription database and found that women between ages 45 and 80 who took GLP-1 drugs were 30% less likely to develop breast cancer. Radiologist Elizabeth McDonald of the University of Pennsylvania, a co-author of that study, said the protective effect appeared greater than what would be expected from weight loss alone. "The weight loss alone just didn't account for the magnitude of the observed effect," McDonald said, according to NPR.