HIGH-DOSE BICALUTAMIDE FOR ANDROGEN-INDEPENDENT PROSTATE-CANCER - EFFECT OF PRIOR HORMONAL-THERAPY

Purpose: A pilot study of the antiandrogen bicalutamide at 150 mg. a d ay for androgen independent prostate cancer was performed. This study was based on the possibility that androgen independent cases might dis play responses to additional hormonal agents. Materials and Methods: T he study included 31 androgen independent cases with an increasing pro state specific antigen (PSA) and progressive disease. PSA measurements were used as the primary method of assessing response. However, PSA d ecline was also correlated with clinical status. Results: Seven patien ts demonstrated PSA declines of greater than 50% for 2 months or more, for an overall response rate of 22.5%. Responses were observed almost exclusively in patients treated with long-term flutamide as part of a complete androgen blockade regimen (43% response rate) in contrast to patients treated with androgen deprivation without flutamide (6% resp onse rate). Of the 7 PSA responding patients bicalutamide resulted in a significant improvement in performance status and a decrease in anal gesic requirement in 4 and 3 remained asymptomatic. Bicalutamide at 15 0 mg. a day was well tolerated, with the most frequent side effect bei ng mild exacerbation of hot flashes. Conclusions: Bicalutamide at this dose is modestly effective for some patients with androgen independen t prostate cancer, particularly for those previously treated with long -term flutamide, This study indicates that previous antiandrogen thera py alters the response to subsequent hormonal agents.