Clinical outcome of maximum androgen blockade using flutamide as second-line hormonal therapy for hormone-refractory prostate cancer.

Abstract

To investigate the efficacy of maximum androgen blockade (MAB) using flutamide as second-line hormonal therapy for advanced hormone-refractory prostate cancer (HRPC). The study included 55 patients with HRPC who were treated with MAB using flutamide (375 mg daily) as second-line hormonal therapy. All patients had previously received bicalutamide combined with either surgical or medical castration as first-line hormonal therapy, which failed. The effect of the second-line therapy was evaluated by serum prostate-specific antigen (PSA) level alone, and the response defined as a decrease of >50% from the baseline PSA at the start of second-line therapy. On initiating second-line hormonal therapy there was a reduction in the PSA level in 25 of the 55 patients (45%), among whom 12 (22%) were regarded as responders, while the PSA level continued to increase in the remaining 30 (55%). The median (range) duration of the PSA response was 6 (1-13) months. During the observation period there were no severe side-effects from the second-line MAB therapy. Patients without bone metastases or whose disease progressed >1 year after first-line therapy had a significantly higher incidence of PSA response to second-line therapy, despite no significant effect of other factors examined on the PSA response to second-line therapy. Furthermore, the cause-specific survival in responders to second-line therapy was significantly better than that in nonresponders; however, multivariate analysis showed that no factors, including response to second-line therapy, could be used as independent predictors of cause-specific survival. MAB using flutamide as second-line hormonal therapy can give a comparatively favourable PSA response with no severe side-effects; therefore, this therapy may be suitable for patients with HRPC after primary MAB using bicalutamide has failed, particularly in those with no bone metastases or whose disease has progressed for >1 year after first-line therapy.