Androgen deprivation therapy is the gold standard for treating advanced prostatic cancer in patients, but the application of combined androgen blockade as a first-line hormone therapy remains controversial. To date, there are no reports that compare a regimen of androgen blockade using GnRH agonists plus bicalutamide to a regimen of GnRH antagonists plus bicalutamide. The aim of this prospective study was to investigate whether GnRH agonists or antagonists, when combined with bicalutamide, demonstrate effective prostate-specific antigen (PSA) dynamics in prostate cancer patients.
Patients with prostate cancer (n = 86) received bicalutamide (80 mg once daily) plus either GnRH antagonist (degarelix acetate) or GnRH agonist (leuprorelin acetate or goserelin acetate) for 12 weeks. Primary end point was the rate of PSA change at 4 weeks (UMIN000013151). Wilcoxon signed-rank test was used to determine whether these combinations caused rapid decline of PSA.
|GnRH antagonist (n = 43)||GnRH agonist (n = 43)|
|Age (median)||55–84 (72)||50–87 (72)|
|< = 6||2||6|
|> = 8||24||21|
|ECOG PS 0 / 1 / 2-3||38 / 5 / 0||41 / 1 / 1|
|Number of patients treated with bicalutamide before GnRH antagonist or agonist administration||5||35|
|Rates of PSA change at weeks 4||10.9%||17.4%|
|Rates of PSA change at weeks 12||1.4%||2.1%|
Rates of PSA change at weeks 4 and 12 were 10.9% and 1.4%, respectively, for the GnRH antagonist cohort, compared to 17.4% and 2.1% for the GnRH agonist cohort. The GnRH antagonist regimen showed rapid decline in PSA at both 4 and 12 weeks; however, these results did not achieve statistical significance, possibly because more patients in the GnRH agonist cohort were pretreated with bicalutamide in order to avoid testosterone surge.
Large scale and/or long term study may demonstrate that GnRH antagonists plus bicalutamide is an effective therapy as initial combined androgen blockade for patients with high grade prostate cancer.
Clinical trial identification
All authors have declared no conflicts of interest.