Long-term effects of finasteride on prostate tissue composition

Area of Science:

• Urology
• Pharmacology
• Medical Imaging

Background:

• Benign prostatic hyperplasia (BPH) is a common condition in aging men.
• Finasteride is a 5α-reductase inhibitor used to treat BPH.
• The long-term effects of finasteride on prostate tissue composition and its mechanism of action require further elucidation.

Purpose of the Study:

• To investigate the long-term impact of finasteride on prostate tissue composition.
• To correlate these tissue changes with clinical outcomes in BPH patients.
• To determine if finasteride has a selective effect on the prostate's transition zone.

Main Methods:

• A 24-month open-label extension study involving 19 men with BPH who responded to 6-month finasteride treatment.
• Serial magnetic resonance imaging (MRI) and prostate biopsies for morphometric analysis were conducted.
• Measurements included prostate volume, transition zone proportion, and epithelial/stromal composition over time.

Main Results:

• Finasteride treatment led to sustained decreases in BPH symptoms, dihydrotestosterone, prostate-specific antigen, and prostate volume.
• Prostate epithelium volume progressively contracted from 19.2% at baseline to 6.4% after long-term treatment (24-30 months).
• Epithelial contraction occurred similarly in peripheral and transition zones, with the transition zone maintaining its relative proportion of whole prostate volume.

Conclusions:

• Long-term finasteride treatment induces significant and progressive involution of prostate epithelium.
• The mechanism for sustained finasteride action in BPH appears to be the progressive contraction of prostate epithelium.
• Finasteride's effects on prostate epithelium are not selective for the transition zone, impacting both peripheral and transition zones similarly.