title: Long-term effects of finasteride on prostate tissue composition.
abstract: OBJECTIVE
  To determine the long-term effects of finasteride treatment on prostate tissue composition; to relate these effects to clinical outcomes; and to test the hypothesis that finasteride exerts a selective or preferential action on the transition zone.
  
  
  METHODS
  Nineteen men with symptomatic benign prostatic hyperplasia (BPH) who completed a 6-month double-blind trial of finasteride were enrolled in a 24-month open-label extension study of drug responders. Magnetic resonance imaging and prostate biopsy for morphometric analysis were performed together 70 times: at baseline (n = 19), after treatment periods of intermediate duration (6 to 18 months, n = 32), and after long-term drug treatment (24 to 30 months, n = 19). At baseline, prostate volume averaged 51 cc, of which 57% was transition zone.
  
  
  RESULTS
  Decreases in symptom score, dihydrotestosterone and prostate-specific antigen levels, and prostate volume occurred at 6 months (P <0.01), stabilized, and were maintained without further long-term decreases. Prostate epithelium contracted progressively from baseline (19.2% tissue composition; 6.0-cc volume; 3.2 stroma/epithelial ratio) to intermediate (12.5%, 3.3 cc, and 5.6, respectively) to long-term treatment (6.4%, 2.0 cc, and 17.4, respectively, P <0.01 for all). Percent epithelial contraction was similar in the peripheral and transition zones (P = NS). The transition zone remained a relatively constant proportion (53% to 58%) of whole-prostate volume from baseline to long-term observation.
  
  
  CONCLUSIONS
  Long-term finasteride treatment (24 to 30 months) results in a marked involution of the prostate epithelium, which continues to progress for many months after clinical effects stabilize. The effect on the epithelium is similar in the peripheral and transition zones for both morphometric and volumetric changes. Progressive contraction of the prostate epithelium appears to constitute the underlying mechanism for sustained action of finasteride.
authors: Department of Urology, University of California, Los Angeles School of Medicine, USA.
authors: L S
authors: LS
authors: Marks
authors: A W
authors: AW
authors: Partin
authors: F J
authors: FJ
authors: Dorey
authors: G J
authors: GJ
authors: Gormley
authors: J I
authors: JI
authors: Epstein
authors: J B
authors: JB
authors: Garris
authors: M L
authors: ML
authors: Macairan
authors: E D
authors: ED
authors: Shery
authors: P B
authors: PB
authors: Santos
authors: E
authors: E
authors: Stoner
authors: J B
authors: JB
authors: deKernion
mesh_terms: D004311:Double-Blind Method; D004791:Enzyme Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use; D018120:Finasteride / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000187:drug effects* / Q000473:pathology*; D011470:Prostatic Hyperplasia / Q000188:drug therapy; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D018120:Finasteride