Glucagon-like peptide 1 receptor agonists and cancer risk: the good, the bad and the unknown

Glucagon-like peptide 1 receptor agonists (GLP1RAs) are widely used for the treatment of type 2 diabetes mellitus (T2DM) and, at higher doses, obesity. Both T2DM and obesity are associated with a higher risk of cancer, which can be reduced by intentional weight loss, whereas effects of a reduction in hyperglycaemia are uncertain. GLP1RAs might have further direct effects, either beneficial or detrimental, on the development of specific malignancies. Evidence from preclinical and clinical studies suggests heterogeneous effects of GLP1RAs on cancer risk: the incidence of hepatocellular, oesophageal, endometrial, ovarian and prostate cancers might be reduced, whereas safety concerns persist with respect to thyroid (both medullary and non-medullary) carcinomas. Conversely, initial concerns on the risk of pancreatic cancer have not been confirmed. Nonetheless, the interpretation of current data is limited by detection and prescription biases in observational studies as well as insufficient follow-up and number of events in randomized trials. In this Review, we summarize current preclinical and clinical evidence, showing that the risk-benefit profile of GLP1RAs remains favourable in individuals with T2DM and obesity, although caution is warranted in those with a low cardiometabolic risk, for whom the potential risks of cancer might outweigh any expected benefits; conversely, the potential use of GLP1RAs as adjuvant therapies for certain forms of cancer needs to be further investigated.