Bicalutamide and flutamide, each in combination with luteinizing hormone-releasing hormone analogs, in advanced prostate cancer: Exploratory analysis of impact of extent of disease by bone scan on outcome

Objectives: We performed an exploratory analysis to determine whether there was a difference between two antiandrogen-plus-luteinizing hormone-releasing hormone analogs (LHRHas) combinations in patients with minimal or extensive disease. Materials and Methods: Data from a prospective, randomized, double-blind study with a median follow-up of 160 weeks were used to perform an exploratory analysis of outcome with 2 combined androgen blockade regimens in 813 advanced prostate cancer patients based on disease status at entry (minimal or extensive disease). A total of 404 patients received bicalutamide plus LHRHa, and 409 patients received flutamide plus LHRHa. Patients were grouped prospectively by 'extent of disease' as determined by bone scan: minimal disease was defined as zero to five lesions, while extensive disease was defined as greater than or equal to six lesions. Patients with no lesions on bone scan (0 lesions) had to have at least one measurable nonskeletal metastasis. Results: Patients with minimal disease receiving bicalutamide plus LHRHa demonstrated a trend to longer survival as reflected by a hazard ratio (HR) of 0.79 (95% confidence interval 0.59-1.07), but this was not statistically significant. In the extensive disease group, the effects of bicalutamide plus LHRHa and flutamide plus LHRHa on disease progression and survival were similar (HR 0.96 and 0.90, respectively). Conclusions: Our results are consistent with previously published data demonstrating that patients with stage D₂ prostate cancer and minimal disease have a better outcome than patients with extensive disease. In the patients with minimal disease per bone scan, there was a trend toward a benefit for bicalutamide plus LHRHa compared with flutamide plus LHRHa in terms of survival, but not in terms of disease progression.