Dihydrotestosterone levels and survival in screening-detected prostate cancer: a 15-yr follow-up study.

OBJECTIVES: It has been hypothesized that dihydrotestosterone (DHT), the main intracellular androgen in the prostate, affects prostatic tumour progression. In this study, we evaluated serum DHT levels at the time of prostate-cancer diagnosis in relation to survival.
METHODS: Sixty-five screening-detected patients diagnosed in 1988-1989 were followed for 15 yr. DHT levels at the time of diagnosis were determined through radio-immuno assay. Subjects were followed up through the nationwide tax register. Medical records of all dead subjects were reviewed, and cause of death was established by an endpoint committee. Data were analyzed through Kaplan-Meier estimation and Cox proportional-hazards regression.
RESULTS: Seventeen of 41 deaths in the cohort during follow-up were attributed to prostate cancer. Patients with DHT above the median had a significant better prostate-cancer-specific survival than those with DHT below the median (log rank p=0.0075). In the univariate analyses, one unit increase in DHT was associated with a hazard ratio (HR) of 0.14 (95% CI=0.02-0.93). In the multivariate model, including prostate-specific antigen level, the association between DHT and prostate-cancer-specific survival was not significant (HR=0.18; 95% CI=0.02-1.6). DHT level below the median remained significantly associated with decreased survival in the multivariate model (HR=0.23; 95% CI=0.06-0.90). No association was found between DHT level and hazard of dying from causes other than prostate cancer.
CONCLUSIONS: Although the prognostic value of DHT levels at diagnosis remains unclear, these results provides evidence of an association between low DHT and decreased survival in prostate cancer patients.