Can effect of finasteride on prostate-specific antigen be used to decrease repeat prostate biopsy?
OBJECTIVES: Patients often undergo multiple prostate biopsies for persistently elevated prostate-specific antigen (PSA) levels. Finasteride decreases serum PSA by approximately 50%. We performed a pilot study to examine the correlation among finasteride, PSA, and PSA density (PSAD) to identify patients who could be excluded from repeat prostate biopsy. METHODS: We performed a prospective study from 2001 to 2002 on 25 men with elevated PSA levels. These patients had prior negative prostate biopsy findings. At study onset, the patients' PSA level and PSAD were measured. Patients were instructed to take finasteride 5 mg for 6 months. PSA and PSAD determination and prostate biopsies were repeated at 6 months and the findings compared with the initial results. RESULTS: The mean patient age was 67.2 years (median 62). The median PSA level was 8.3 ng/dL at study entry (mean 9.34) and 4.6 ng/dL (mean 5.09) at 6 months. The median PSAD was 0.18 (mean 0.20) at study entry and 0.09 (mean 0.12) at 6 months. Of the 23 patients who completed the study, 6 (26%) were diagnosed with prostate cancer. At study entry, the median PSA level in those with prostate cancer was 9.6 ng/dL and was 5.8 ng/dL at 6 months. Patients without prostate cancer on repeat biopsy had a 44% decrease in PSAD. Patients with prostate cancer had a 5% decrease in PSAD. CONCLUSIONS: The results of our study have demonstrated that patients without prostate cancer have a greater decrease in PSAD when taking finasteride than those with prostate cancer. This pilot study had a small population with limited power, and a repeat prospective study with a larger population is warranted.