PURPOSE: To analyze the effect of the oral antidiabetic drug metformin on PSA level, free-to-total PSA ratio (f/t-ratio), PCa incidence and grade as well as mortality in men participating in a population-based screening trial.
METHODS: Data from 4,314 men aged 55-70 years from a population-based PSA-screening trial (ERSPC Aarau) were analyzed. Information on metformin exposure was obtained by a self-administered questionnaire. Serum PSA threshold at ≥3 ng/ml triggered prostate biopsy. Data on PCa incidence and mortality were obtained through registry linkages.
RESULTS: Median follow-up time was 7.6 years. Mean age at baseline was 65.5 years (±SD 4.4). In all, n = 150 (3.5 %) men used metformin [metf+]. Mean baseline PSA levels were comparable between both groups ([metf+] 1.6 ng/ml ± 2.4 vs. [metf-] 1.8ug/l ± 2.2, p = 0.4) while f/t-ratio was slightly higher in metformin users ([metf+] 30.7 % ± 10.9 vs. [metf-] 27.3 % ± 10.9, p = 0.01). Overall, n = 372 (8.6 %) PCa cases were detected. Neither cumulative PCa incidence (n = 11; 7.3 % [metf+] vs. n = 361 8.7 % [metf-]; p = 0.5) nor d`Amico risk groups were significantly different between both groups. One man in each group (metf+ 0.7 % and metf- 0.02 %) died from PCa (p < 0.0001), respectively. All-cause mortality was significantly higher among met + compared to met- (adjusted OR 2.50, 95 %CI 1.59-3.82; p = 0.0001).
CONCLUSION: No significant differences in PSA levels or PCa incidence and grade were observed. The slightly higher f/t-ratio did not result in lower PCa detection rate. Metformin users were at significantly higher risk of all-cause mortality. The relatively small number of men on metformin is a main limitation of the study.
Randazzo M, Beatrice J, Huber A, Grobholz R, Manka L, Wyler SF, Chun FF, Recker F, Kwiatkowski M. Are you the author?
Department of Urology, Cantonal Hospital Aarau, Aarau, 5001, Switzerland.
Reference: World J Urol. 2014 Oct 31. Epub ahead of print.