Recovery of serum prostate specific antigen value after interruption of antiandrogen therapy with allylestrenol for benign prostatic hyperplasia.

Decrease in serum prostate specific antigen (PSA) concentration is inevitably associated with antiandrogen therapy for benign prostatic hyperplasia (BPH), and might mask the presence of prostate cancer or delay its diagnosis. To determine the appropriate timepoint for determination of correct PSA value, we sequentially measured serum PSA and testosterone levels after discontinuation of antiandrogen therapy for BPH. With informed consent, 12 patients (72.8 +/- 12.2* years old) with BPH were treated with allylestrenol 50 mg/day for 4 months. Serum testosterone and PSA concentrations were determined before and just after treatment, as well as every month after treatment up to 3 months. After treatment with allylestrenol for 4 months, mean serum testosterone and PSA levels were significantly decreased from 408 +/- 136* to 87.9 +/- 76.2* ng/dl, and from 2.81 +/- 0.87* to 2.04 +/- 0.82* ng/ml, respectively. The mean serum PSA level recovered to the pretreatment level within 2 months and mean serum testosterone concentration within one month after discontinuation of administration. In conclusion, during treatment of BPH with antiandrogen allylestrenol, a two-month washout is adequate for determination of correct PSA value (*: M +/- SD).