Effects of bicalutamide and leuprolide on prostate-specific antigen (PSA), acid phosphatase (ACP) and prostatic acid phosphatase (PAP) in men with benign prostatic hyperplasia (BPH)

The effects of the nonsteroidal antiandrogen bicalutamide (Casodex(TM)) and the luteinizing hormone releasing hormone agonist leuprolide depot (Procren Depot(TM). Lupron Depot(TM)) on serum prostate-specific antigen (PSA), acid phosphatase (ACP), and prostatic acid phosphatase (PAP) in patients with benign prostatic hyperplasia (BPH) were determined. Thirty patients with BPH were randomised to receive bicalutamide 50 mg orally once daily or a placebo for 24 weeks, followed by 24 weeks of follow-up (bicalutamide study). In another study 55 men were randomised between 3.75 mg leuprolide depot intramuscularly at every 28 days for 24 weeks or placebo injections (leuprolide study). In both studies blood sampling was performed at baseline, at week 12 at week 24 and 24 weeks after the end of therapy. Androgen suppression with bicalutamide 50 mg; daily for 24 weeks resulted in a median of 56% reduction of PSA (P < 0.001 when compared to placebo). Acid phosphatase and PAP did not change. Leuprolide resulted in a median of 87% reduction of serum PSA (P < 0.001) and a 39% reduction of PAP (P = 0.023), whereas ACP was unchanged. Both bicalutamide and leuprolide induced a pronounced decline in serum PSA in BPH patients. The studies suggest a stronger androgen suppressive effect of leuprolide than of bicalutamide, but this difference might largely be due to too low a dosage of bicalutamide. ACP and PAP were relatively insensitive to androgen suppression. Our study suggests a different degree of androgen suppression on PSA originating from benign tissue versus cancer tissue, and that the direction of this discrepancy might be different for various androgen suppressive regimens.