Purpose: To compare in a randomized clinical trial the therapeutic efficacy of the nonsteroidal antiandrogen flutamide 250 mg tid to testicular androgen suppression by orchidectomy in patients with metastatic prostate cancer.
Patients and methods: Between 1989 and 1991, 104 patients aged 74 +/- 8 years with newly diagnosed metastatic prostate cancer, an ECOG performance status 0-2 and no prior hormone manipulation or chemotherapy, were randomized to receive flutamide 250 mg tid (54 patients) or orchidectomy (50 patients). Patients were evaluated at entry and at months 3, 6, 12, 18 and 24. The primary endpoint was duration of progression-free survival, progression being defined as an increase in PSA> 50% over the nadir value at 2 consecutive months or a single PSA rise > 50% over the nadir value with another objective parameter. At progression, the treatment was left to the discretion of the attending urologist.
Results: 16 patients (10 flutamide, 6 orchidectomy) are not evaluable. 86 had a minimum follow-up of 36 months, 36/42 and 41/44 have progressed in the orchidectomy and flutamide group with a time of failure of 419 and 496 days (p = 0.32); median time to progression was almost identical in both groups (370 vs. 396 days p = 0.9); overall survival at 69 months irrespective of treatment at relapse was identical in both groups. Side effects were dominated by gynecomastia, hot flushes in both groups, breast tenderness and diarrhea in the flutamide group. Overall, 4 (10%) of the patients in the flutamide group withdrew from therapy because of side effects. The impact of flutamide on sexual potency was not assessed because of the advanced age of the patients. Serum testosterone rose by 50% over baseline level at month 3 to plateau at 25% over baseline level at month 12.
Conclusion: Although affected by the lack of a clear statistical power due to the small number of patients in each arm, this study shows that in spite of a constant elevation of serum testosterone (25% over baseline) flutamide 250 mg tid may be a reasonable alternative to castration in highly selected patients with well to moderately differentiated low volume metastatic prostate cancer and wishing to avoid the side effects of androgen deprivation, provided they are closely monitored and ready to switch to standard androgen deprivation in the presence of untolerable side effects or suboptimal treatment efficacy as assessed by the inability to achieve a low PSA nadir.