MP86-07 ASSOCIATION OF METFORMIN USE WITH PROSTATE CANCER INCIDENCE IN A PROSPECTIVE SCREENING TRIAL (ERSPC AARAU)

INTRODUCTION AND OBJECTIVES: There is conflicting data regarding the effect of the oral antidiabetic drug metformin on prostate cancer (PCa) incidence and mortality. We aimed to assess the effect of metformin on PCa incidence and mortality in men participating in a prospective, population-based screening trial. METHODS: Data of men who underwent PSA-screening in our population-based screening trial (ERSPC Aarau) were analysed. Information on metformin exposure before biopsy was obtained by a selfadministered questionnaire. Cox regression analysis was used to examine the relationship between covariates and PCa incidence. RESULTS: Overall, 4,314 men were observed during a mean follow-up time of 7.3 ( SD2.3) years. Mean age at baseline was 65.5 years (65.5 SD 4.4). Overall, n1⁄4150 (3.5%) men used metformin [metfþ] at baseline. Of those, 80% (88 of 110) who were actively screened during follow-up visit were still on metformin after 4 years whereas 105 men had new [metfþ] exposure. Mean baseline PSAlevels were comparable between both groups ([metfþ] 1.6ng/ml 2.4 vs. [metf-] 1.8ug/l 2.2, p1⁄40.4) while f/t-ratio was slightly higher in metformin users ([metfþ] 30.7% 10.9 vs. [metf-] 27.3% 10.9, p1⁄40.01). Overall, n1⁄4372 (8.6%) PCa cases were detected. Neither cumulative PCa incidence (n1⁄411; 7.3% [metfþ] vs. n1⁄4361 8.7% [metf-]; p1⁄40.5) nor d’Amico risk groups were significantly different between both groups. On multivariate analysis, only increasing baseline PSA (HR 1.11, 95%CI 1.09-1.13; p