Effectiveness of cyproterone acetate in achieving castration and preventing luteinizing hormone releasing hormone analogue induced testosterone surge in patients with prostate cancer.

PURPOSE

To our knowledge this study represents the first analysis monitoring the efficacy of cyproterone acetate (CPA) monotherapy for achieving castrate testosterone levels prior to administering a luteinizing hormone-releasing analogue (LHRHA) for treating prostate cancer in the prostate specific antigen (PSA) era.

MATERIALS AND METHODS

Patients with untreated locally advanced or metastatic prostate cancer were recruited prospectively. Treatment involved a 28-day course of oral cyproterone acetate and LHRHA depot injection on day 14. Patients had serum PSA, luteinizing hormone and testosterone monitored at intervals during a 56-day period.

RESULTS

A total of 15 patients with a mean age of 74 years completed the study. Near castrate serum testosterone was achieved on day 7 (mean +/- 95% CI 83.38 +/- 17.87 ng/dl). There was a significant testosterone increase after LHRHA administration on day 14 compared with the level of 160.23 +/- 36.60 ng/dl on day 16 (p <0.01). Serum luteinizing hormone mirrored testosterone, increasing from a mean of 4.93 +/- 0.61 to 15.4 +/- 6.12 nmol/l after LHRHA administration (p <0.01). Mean serum PSA demonstrated a decrease from 199.25 +/- 6.12 microg/l at day 0 to 43.77 +/- 33.08 microg/l by day 56. There was no increase in serum PSA after LHRHA administration.

CONCLUSIONS

Two weeks of priming with CPA does not eliminate the surge in serum testosterone (testosterone flare) upon LHRHA administration but the testosterone increase does not exceed pretreatment levels. Furthermore, 2 weeks of CPA may not offer a benefit over 1 week in lowering serum testosterone. Finally, there is no increase in serum PSA when LHRHA is administered after priming with CPA.