Greater percent-free testosterone is associated with high-grade prostate cancer in men undergoing prostate biopsy

To analyze the serum androgen concentrations in men who underwent an initial prostate biopsy, focusing on the percent-free testosterone (%FT) as a predictor of low- and high-grade prostate cancer (PCa). Most studies have suggested that the absolute serum testosterone and free testosterone levels are not related to PCa risk. However, to date, the concurrent effect of free and total testosterone levels has not been evaluated. In particular, the association of the %FT (free testosterone/total testosterone) with PCa risk has not been explored.

From 2006 to 2010, we collected data on 812 white Italian men with no history of PCa who underwent 12-core biopsy. The testosterone, free testosterone, and %FT (free testosterone/total testosterone) were examined as predictors of low-grade (Gleason score of ≤ 6) and high-grade (Gleason score ≥ 7) PCa using crude and adjusted multinomial logistic regression analysis.

On multivariate analysis, testosterone (P ≥ .11) and free testosterone (P ≥ .45) were not significantly associated with low- or high-grade PCa. A greater %FT level significantly predicted high-grade PCa on both crude (P = .01) and multivariate (P = .02) analysis but not low-grade PCa (P ≥ .38). When examined in tertiles, men in the greatest %FT tertile had a significant twofold increased risk of high-grade PCa (odds ratio 2.04, 95% confidence interval 1.23-3.37, P = .005).

In white Italian men, a greater %FT level was associated with an increased risk of high-grade PCa on initial prostate biopsy. These findings suggest that a high %FT level, rather than the absolute androgen levels, might be associated with high-grade PCa. Additional studies are needed to confirm our findings.