Clinical Outcomes and Testosterone Levels Following Continuous Androgen Deprivation in Patients with Relapsing or Locally Advanced Prostate Cancer: A Post Hoc Analysis of the ICELAND Study.

PURPOSE: Lower serum testosterone levels correlate with improved cause specific survival and longer time to progression in year 1 of continuous androgen deprivation in men with prostate cancer. ICELAND was a large European study demonstrating the efficacy of leuprorelin (Eligard®) during continuous androgen deprivation. In this post hoc analysis we investigated serum testosterone levels within year 1 of continuous androgen deprivation to determine survival and time to progression.

MATERIALS AND

METHODS

In ICELAND (ClinicalTrials.gov NCT00378690) patients with locally advanced or relapsing nonmetastatic prostate cancer and with prostate specific antigen 1 ng/ml or less following 6-month induction with leuprorelin 3-month depot 22.5 mg (plus bicalutamide 50 mg per day for 1 month) were randomized 1:1 to continuous androgen deprivation (361) or intermittent androgen deprivation (340) with leuprorelin for 36 months. Patients receiving continuous androgen deprivation were stratified by minimum, median and maximum testosterone levels during year 1 of therapy into 20 or less, greater than 20 to 50 and greater than 50 ng/dl subgroups. Cause specific survival and time to prostate specific antigen (castrate resistant prostate cancer) progression were analyzed.

RESULTS

A total of 90.1%, 83.5% and 74.5% of patients receiving continuous androgen deprivation achieved minimum, median and maximum serum testosterone levels of 20 ng/dl or less, respectively. Cause specific survival rates and time to prostate specific antigen progression did not differ among the testosterone subgroups.

CONCLUSIONS

In patients receiving continuous androgen deprivation cause specific survival and time to prostate specific antigen progression did not differ according to testosterone levels in year 1 of therapy. This finding may in part be due to the induction period and the effectiveness of leuprorelin in lowering testosterone.