Low free testosterone levels predict disease reclassification in men with prostate cancer undergoing active surveillance.

ABSTRACT

OBJECTIVE: To determine whether total testosterone and free testosterone levels predict disease reclassification in a cohort of men with prostate cancer (PCa) on active surveillance (AS). PATIENTS AND METHODS: Total testosterone and free testosterone concentrations were determined at the time the men began the AS protocol. Statistical analysis was performed using Student's t-test and a chi-squared test to compare groups. Odds ratios (ORs) with 95% confidence intervals (CIs) were obtained using univariate logistic regression. Receiver-operator characteristic curves were generated to determine the investigated testosterone thresholds. Kaplan-Meier curves were used to estimate time to disease reclassification. A Cox proportional hazard regression model was used for multivariate analysis. RESULTS: A total of 154 men were included in the AS cohort, of whom 54 (35%) progressed to active treatment. Men who had disease reclassification had significantly lower free testosterone levels than those who were not reclassified (0.75 vs 1.02 ng/dL, P = 0.03). Men with free testosterone levels <0.45 ng/dL had a higher rate of disease reclassification than patients with free testosterone levels ≥0.45 (P = 0.032). Free testosterone levels <0.45 ng/dL were associated with a several-fold increase in the risk of disease reclassification (OR 4.3, 95% CI 1.25-14.73). Multivariate analysis showed that free testosterone and family history of PCa were independent predictors of disease reclassification. CONCLUSIONS: Free testosterone levels were lower in men with PCa who had reclassification during AS. Men with moderately severe reductions in free testosterone level are at increased risk of disease reclassification.