Inhibition of PSA flare in prostate cancer patients by administration of flutamide for 2 weeks before initiation of treatment with slow-releasing LH-RH agonist

Abstract

Background. A prospective randomized study was designed to determine whether flutamide (FLU) administered before treatment with a luteinizing hormone-releasing hormone agonist (LH-RHa) prevented prostate-specific antigen (PSA) flare in prostate cancer patients.

Methods. Prostate cancer patients were randomized into two groups and received either FLU (n = 11) or no pretreatment (n = 13) for 2 weeks before the initial injection of LH-RHa. LH-RHa (every 4 weeks) and FLU (every day) were administered throughout the period of this study. Blood samples, for the determination of PSA, testosterone (T), and luteinizing hormone levels, were collected before FLU administration, and before and 2, 7, 14, 28, 56, and 84 days after the first administration of LH-RHa.

Results. Treatment with FLU prior to LH-RHa induced an early decline in PSA level. The mean PSA level showed no significant secondary rise after LH-RHa administration in those patients with FLU pretreatment. Patients in both groups showed T flare after the first LH-RHa administration. However, the number of patients with PSA flare was significantly lower in patients with prior FLU administration than in those with LH-RHa alone.

Conclusion. These results clearly demonstrate that, in patients with prostatic cancer, the administration of FLU for 2 weeks prior to the first LH-RHa administration is effective in preventing PSA flare, as well as in inducing an early decline in PSA levels.