Bicalutamide vs cyproterone acetate in preventing flare with LHRH analogue therapy for prostate cancer--a pilot study

To evaluate the efficacy of bicalutamide vs cyproterone acetate in preventing PSA flare (as a surrogate for tumour flare) for patients requiring luteinizing hormone-releasing hormone (LHRH) analogue therapy for prostate cancer.

In this pilot study, 40 men were randomized 1 : 1 to bicalutamide 50 mg o.d. or cyproterone acetate 100 mg t.i.d. 5 days prior to goserelin acetate and continued for 21 days thereafter. PSA, luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone were obtained before treatment and on days 6, 8, 10, 16, 21 and 28. Primary end point was PSA. Hormone profile and clinical features including urinary symptoms and bone pain were secondary end points.

Both groups were equally matched apart from serum creatinine and ALP. The speed and magnitude of the percentage change in median PSA from baseline was increased for the CPA group but there was no statistically significant difference in the two groups. Although those receiving bicalutamide all showed a testosterone peak, this remained within the normal range. No difference in the frequency of drug-specific adverse events was found. None of the patients died or developed cord compression during the study period.

Bicalutamide is able to suppress the initial PSA surge as effectively as cyproterone acetate albeit slightly delayed. A statement whether bicalutamide is equally good at preventing clinical flare cannot be made and should be assessed in an appropriately powered study.