[Rebound of prostate specific antigen after discontinuation of antiandrogen therapy for benign prostatic hyperplasia].

We compared the prostate specific antigen (PSA) levels in benign prostatic hyperplasia (BPH) patients with antiandrogen chlormadinone acetate (CMA) or allylestrenol (AE) before and during the treatment. We also investigated the serial change of PSA levels before, during and after discontinuation of antiandrogen therapy. Fifty-one BPH patients with normal PSA levels were treated with CMA or AE for 16 weeks. The mean serum PSA level significantly decreased after the treatment from 1.9 +/- 1.0 ng/ml to 1.1 +/- 0.7 ng/ml (M +/- SD). We discontinued medication with informed consent and the patients were carefully monitored for another 16 weeks. Nineteen patients were followed for 32 weeks. The mean serum PSA level decreased significantly from 2.0 +/- 1.0 ng/ml to 1.1 +/- 0.5 ng/ml (M +/- SD) and recovered approximately to the pretreatment level (1.7 +/- 1.1 ng/ml) at the end of this study. We found only one patient whose PSA was slightly elevated to a subnormal range (4.3 ng/ml) after discontinuation of therapy. The other BPH patients with normal PSA levels showed no excessive increase in PSA levels beyond the normal limit after discontinuation of antiandrogen therapy compared with the pretreatment baseline. In conclusion, BPH patients with a marked increase in PSA after discontinuation of antiandrogen therapy should be checked for prostate cancer.