5 alpha-Reductase inhibitor is less effective in men with small prostate volume and low serum prostatic specific antigen level

Background/Purpose: Large total prostate volumes (TPVs) or high serum prostate-specific antigen (PSA) levels indicate high-risk clinical progression of benign prostatic hyperplasia. This prospective study investigated the treatment outcome of combined 5 alpha-reductase inhibitor and alpha-blocker in patients with and without large TPVs or high PSA levels. ;Methods: Men aged >= 45 years with International Prostate Symptom scores (IPSS) >= 8, TPV >= 20 mL, and maximum flow rate <= 15 mL/s received a combination therapy (dutasteride plus doxaben) for 2 years. Patients with baseline PSA >= 4 ng/mL underwent prostatic biopsy for excluding malignancy. The changes in the parameters from baseline to 24 months after combination therapy were compared in those with and without TPV >= 40 mL or PSA levels >= 1.5 ng/mL. ;Results: A total of 285 patients (mean age 72 +/- 9 years) completed the study. Combination therapy resulted in significant continuous improvement in IPSS, quality of life index, maximum flow rate, and postvoid residual (all p < 0.0001) regardless of baseline TPV or PSA levels. However, only patients with baseline TPV >= 40 mL had significant improvements in IPSS-storage subscore, voided volume, reduction in TPV, transitional zone index, and PSA levels. In addition, patients with baseline TPV < 40 mL and PSA < 1.5 ng/mL had neither a reduction in TPV nor a decrease in serum PSA level. ;Conclusion: A high TPV indicates more outlet resistance, whereas elevated serum PSA level reflects glandular proliferation. Thus, patients with TPV<40 mL and low PSA levels has less benefit from 5 alpha-reductase inhibitor therapy. The therapeutic effect of combined treatment may arise mainly from the alpha-blocker in these patients. Copyright (C) 2013, Elsevier Taiwan LLC & Formosan Medical Association. All rights reserved.