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Influence of finasteride on free and total serum prostate specific antigen levels in men with benign prostatic hyperplasia.

Pannek J, Marks LS, Pearson JD, Rittenhouse HG, Chan DW, Shery ED,
Gormley GJ, Subong EN, Kelley CA, Stoner E, Partin AW
J Urol 1998 Feb;159(2):449-53

James Buchanan Brady Urological Institute and the Department of Clinical Chemistry,
Johns Hopkins Medical Institution, Baltimore, Maryland, USA.

PURPOSE -- Finasteride therapy for benign prostatic hyperplasia (BPH) results in a marked lowering of serum prostate specific antigen (PSA) levels. However, little is known about the effect of finasteride on unbound or free serum levels of PSA. Such information would be important since percent free PSA may substantially improve the cancer specificity of PSA testing. Thus, we prospectively studied the effect of finasteride therapy on total and free serum PSA levels.

MATERIALS AND METHODS -- In a randomized, placebo controlled, double-blind trial 40 men with histologically confirmed BPH (age range 52 to 78 years) were treated with either 5 mg. finasteride daily (26 patients) for 9 months or placebo (14) for 6 months. Prostate volume was assessed by transrectal ultrasound. Serum levels of free and total PSA were measured from archived serum samples stored at -70C at baseline and for as long as 9 months of treatment.

RESULTS -- In the finasteride group mean total PSA levels declined from 3.0 ng./ml. at baseline to 1.5 ng./ml. after 6 months of treatment (50% decrease, p <0.01). In the placebo group, with similar baseline levels, no significant change was observed. PSA density declined significantly in finasteride treated men (p <0.01) but not in men receiving placebo. The mean percent free PSA (13 to 17% at baseline) was not altered significantly by finasteride or placebo.

CONCLUSIONS -- Total PSA serum levels decreased by an average of 50% during finasteride therapy but percent free PSA did not change significantly. This information is potentially useful in the interpretation of PSA data used for early detection of prostate cancer in men receiving finasteride. However, further studies are required to demonstrate the use of percent free PSA to detect the development of cancer.

Prostate tissue composition and response to finasteride in men with symptomatic benign prostatic hyperplasia.

Marks LS, Partin AW, Gormley GJ, Dorey FJ, Shery ED, Garris JB,
Subong EN, Stoner E, deKernion JB
J Urol 1997 Jun;157(6):2171-8

Department of Surgery/Urology, UCLA School of Medicine, USA.

PURPOSE -- We sought to quantify prostate tissue changes induced by finasteride and to identify a predictor of finasteride response in men with symptomatic benign prostatic hyperplasia (BPH) via a randomized, placebo controlled, double-blind clinical trial.

MATERIALS AND METHODS -- Men with symptomatic BPH (52 to 78 years old) were randomly assigned to 6 months of treatment with finasteride (26) or placebo (15). Outcome measures were clinical (urinary symptom score and flow rate), chemical (serum prostate specific antigen and dihydrotestosterone levels), volumetric (transrectal ultrasound, and magnetic resonance imaging for whole and zonal prostate volumes) and histological (morphometry of prostate sextant biopsies, separated into inner and outer gland segments, to measure the percent epithelium, stroma and glandular lumen).

RESULTS -- In the finasteride group we found a suggestion of decreasing symptom scores and increasing flow rates (not significant) with significant decreases (p < 0.01) in prostate specific antigen (48%), dihydrotestosterone (74%) and prostate volume (21%). Finasteride treatment induced a 55% decrease in inner gland epithelium (p < 0.01) with little effect on stroma or lumina. We also found a linear correlation between pretreatment inner gland epithelial content and prostate volume decrease induced by the drug (tau = 0.58, p = 0.01).

CONCLUSIONS -- Finasteride treatment results in a major suppression of prostate epithelium, which is most pronounced in the inner gland. Moreover, a finasteride induced prostate volume decrease was predictable by quantification of epithelial tissues of the inner gland. These data lend additional support to the emerging concept of transition zone primacy in symptomatic BPH.

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