Low free and bioavailable testosterone levels may predict pathologically-proven high-risk prostate cancer: a prospective, clinical trial.

OBJECTIVE: To determine the predictive value of free and bioavailable testosterone levels on the detection of high-grade prostate cancer proven by histopathological examination of transrectal prostate biopsy specimens. MATERIAL AND METHODS: A total of 405 patients who underwent transrectal prostate biopsy due to high prostatic specific antigen (PSA) (>2.5 ng/mL) and/or abnormal findings at digital rectal examination were included in this study. Blood free and bioavailable testosterone levels were calculated by the formula recommended by International Society for the Study of the Aging Male (ISSAM). The patients were stratified according to the D'Amico classification based on PSA levels and histological outcomes of prostate biopsies as benign, low, intermediate and high-risk prostate cancer. Patients were also divided into five groups according to the percentage of cancerous cores. RESULTS: Prostate cancer was detected in 160 of 405 (39.5%) patients. Total, free and bioavailable testosterone levels did not differ significantly between the patients with benign or malign histology. However, mean free (6.2 vs. 5.2 ng/dL, p=0.02) and bioavailable (151 vs. 125 ng/dL, p=0.001) testosterone levels were found to be significantly different in men with low-intermediate and high-risk prostate cancer. Moreover, a significant correlation was found between free, and bioavailable testosterone levels and percentage of cores with cancer (p=0.002 for free and p=0.016 for bioavailable testosterone, respectively). CONCLUSION: This prospective clinical study demonstrates that reduced levels of calculated blood free and bioavailable testosterone levels are associated with an increased risk of high-grade prostate cancer. Based on these findings blood free and bioavailable testosterone levels may be be thought to be an adjunctive factor in the prediction of high-risk prostate cancer.