Metformin use and the risk of cancer in diabetic patients: A nationwide sample cohort study

Menée à l'aide de données 2010 de l'assurance maladie portant sur 29 974 patients atteints d'un diabète traité par metformine et portant sur 36 653 témoins (âge : plus de 18 ans), cette étude analyse l'association entre ce traitement et le risque de cancer

Résumé en anglais

Metformin is known to have an antitumor effect; however, its effects in the prevention of cancer remain controversial. This study aimed to investigate the association of metformin therapy with the development of cancer. A population-based cohort study was conducted among adult patients with diabetes in 2010 using sample cohort data from the National Health Insurance Service. Metformin users were defined as those who had been prescribed repeated oral metformin administration over a period of ≥ 90 days. The primary endpoint of this study was the new development of cancer from January 1, 2011 to December 31, 2015. A total of 66,627 adult diabetes patients were included in the final analysis; 29,974 were metformin users and 36,653 were controls. In the time-dependent Cox regression model, after multivariable adjustment, the risk for the development of cancer among metformin users was not significantly different from that among controls (hazard ratio: 0.96, 95% confidence interval: 0.89 to 1.03, P=0.250). In the sensitivity analysis, neither low daily dosage (≤1 g/day, P=0.301) nor high daily dosage (>1 g/day, P=0.497) of metformin was significantly associated with the development of cancer between 2011 and 2015. We found no association between metformin therapy and the risk of cancer among diabetes patients, even in the high daily dosage groups of metformin (>1 g/day). However, there might be residual confounders or bias; thus, further prospective, large population-based cohort studies are needed to confirm these findings.