GLP-1 drugs for diabetes and weight loss may influence patients’ cancer risk, usually lowering it but sometimes possibly increasing it, new findings suggest.

U.S. researchers reviewed 10 years of medical records from 43,317 users and 43,315 similar nonusers of Novo Nordisk’s Type 2 diabetes drugs Victoza and Ozempic or its weight-loss medication Wegovy, or Eli Lilly’s Mounjaro for diabetes or Zepbound for weight loss.

All volunteers were at risk for obesity-related cancers.

Each year, out of every thousand participants, 13.6 users of GLP-1 drugs were diagnosed with any of 14 types of cancer, compared to 16.6 nonusers, the researchers reported in JAMA Oncology.

After accounting for individual risk factors, the overall cancer risk was 17% lower in GLP-1 users.

In particular, GLP-1 use was associated with a 25% lower risk of endometrial cancer, a 47% lower risk of ovarian cancer and a 31% lower risk of meningioma.

GLP-1 drugs were also associated with a slight increase in risk for kidney cancer. The increase was not statistically significant, meaning it could have been due to chance – but an earlier study also found a higher risk of kidney cancer with use of GLP-1 drugs for diabetes, the authors note.

Observational studies like this one cannot prove cause and effect, and it’s impossible to know whether any reductions in cancer risk were due to the GLP-1 drugs themselves or to drug-induced weight loss.

Still, the researchers said, “Given that more than 137 million individuals in the U.S. are currently eligible for GLP-1 therapies, even modest changes in cancer risk could have substantial public health implications.”