Effects of Serum Testosterone Levels After 6 Months of Androgen Deprivation Therapy on the Outcome of Patients With Prostate Cancer.

BACKGROUND: Controversy exists about whether testosterone serum levels at a cutoff point of < 50 ng/dL during luteinizing hormone-releasing hormone analogue (LHRHA) treatment are related to the outcome of patients with prostate cancer. We assessed the relationship between serum testosterone levels after 6 months of LHRHA therapy and disease outcome in a consecutive series of patients with prostate cancer. PATIENTS AND METHODS: Serum testosterone levels were measured prospectively in a cohort of patients given LHRHA for 6 months. End points were time to progression (TTP) and overall survival (OS). RESULTS: The study population was 153 patients: 54 with metastatic disease and 99 with biochemical failure. In multivariate analysis, adjustment for age, baseline serum prostatic specific antigen (PSA) levels, Gleason score, and disease stage, testosterone levels < 50 ng/dL failed to be associated with TTP and OS. A cutoff of < 20 ng/dL was associated with a nonsignificant lower risk of progression (adjusted hazard ratio [HR] 0.58; 95% confidence interval [CI] 0.30-1.15; P = .12) and a significant lower risk of death (adjusted HR, 0.19; 95% CI, 0.04-0.76; P = .02). Only 25 patients attained serum testosterone levels < 20 ng/dL. Using a receiver operating characteristic curve (ROC), we found that a testosterone value of 30 ng/dL offered the best overall sensitivity and specificity for prediction of death. Serum testosterone levels < 30 ng/mL were associated with a significantly lower risk of death (adjusted HR, 0.45; 95% CI, 0.22-0.94; P = .034. CONCLUSIONS: Serum testosterone levels lower than the currently adopted cutoff of 50 ng/dL have a prognostic role in patients with prostate cancer receiving LHRHA and are a promising surrogate parameter of LHRHA efficacy.