[Clinical evaluation of flutamide, a pure antiandrogen, in prostatic cancer phase II dose-finding study].

The phase II study of flutamide, a pure anti-androgen, was performed to estimate the clinical doses on 165 hormone untreated or treated patients with prostatic cancer. The hormone-untreated patients were given orally flutamide of 90, 375, 750 or 1,125 mg/day in three divided doses daily for 12 weeks. Responses were not observed at the 90 mg/day dose except for improvement of clinical symptoms. However, an objective response rate of 48.8-46.7% was obtained at 375-1,125 mg/day doses. In hormone-treated patients including cases refractory to the previous hormonal treatment, the objective response rates were 13.3 and 8.3% in 375 and 750 mg/day flutamide groups, respectively. Side effects such as gynecomastia, nausea, vomiting, diarrhea, and abnormal laboratory findings such as the elevation of hepatic transaminases were observed. The incidence increased dose-dependently. Determinations of serum hormone levels revealed an increase in testosterone levels by the use of flutamide. In conclusion 375 mg/day of flutamide is the optimal dose in monotherapy for hormone-untreated patients with prostatic cancer, where the quality of life can be maintained compared with therapies involving testosterone suppression. This dose is also expected to show some efficacy in cases refractory to hormone treatment.