Metformin Treatment Among Men With Diabetes and the Risk Of Prostate Cancer, a Population-Based Historical Cohort Study
Menée en Israël auprès de 145 617 hommes diabétiques âgés de 21 à 90 ans (période de suivi : 2002-2012), cette étude analyse l'association entre un traitement par la metformine et le risque de cancer de la prostate (1 592 cas)
There is conflicting evidence regarding the association between metformin treatment and prostate cancer risk in diabetic men. We investigated this association in an Israeli population-based cohort of 145,617 diabetes-incident men, aged 21-90y, followed over 2002-2012. We implemented a time-dependent covariate Cox model, using weighted cumulative exposure to relate metformin history to prostate cancer risk, adjusting for other glucose-lowering medications, age, ethnicity and socioeconomic status. To adjust for time-varying glucose control variables, we used inverse probability weighting of a marginal structural model. With 666,553 person-years follow-up, 1,592 men were diagnosed with prostate cancer. Metformin exposure in the previous year was positively associated with prostate cancer risk (hazard ratio (HR) per defined daily dose without glucose control adjustment 1.53, 95%CI: 1.19, 1.96; with adjustment 1.42, 95%CI: 1.04, 1.94). However, exposure in the previous 2-7 years was negatively associated with risk (HR without glucose control adjustment 0.58, 95%CI: 0.37, 0.93; with adjustment 0.60, 95%CI: 0.33, 1.09). These positive and negative associations, with previous-year and earlier metformin exposure respectively, need to be confirmed and better understood.