Deferred combined androgen blockade therapy using bicalutamide in patients with hormone-refractory prostate cancer during androgen deprivation monotherapy

Objective To assess the effect of adding bicalutamide on serum prostate-specific antigen (PSA) levels in patients with hormone-refractory prostate cancer (HRPC) during androgen deprivation monotherapy (ADMT). Patients and Methods Forty-four patients with HRPC were treated with deferred combined androgen blockade (CAB) therapy, administering bicalutamide 80 mg once daily. HRPC was defined biochemically as three consecutive rises in PSA level during ADMT. The treatment response was defined as a >= 50% decline in PSA levels. Prognostic values of various pretreatment variables for responsiveness to deferred CAB were determined statistically. When the disease relapsed during deferred CAB, bicalutamide was discontinued and the patients were evaluated for the antiandrogen withdrawal syndrome (AWS). Results Of the 44 patients, 29 (66%) had a PSA response; the median PSA failure-free survival was 9.2+ months. Biopsy Gleason score was the only pretreatment variable predictive of a PSA response (mean Gleason score 7.9 in responders and 8.7 in nonresponders). The PSA doubling time (PSA-DT) was the only statistically significant variable of PSA failure-free survival in a multivariate analysis. The 1- and 2-year PSA failure-free survival rates were 43% and 31% in patients with a PSA-DT of > 4 months, while it was 21% and none, respectively, in those with a PSA-DT of < 4 months. Responders to deferred CAB had a statistically longer cancer-specific survival than nonresponders. None of 20 patients who were evaluated for AWS had the condition. Conclusions Deferred CAB therapy using bicalutamide is effective in patients with progression during ADMT, particularly in those with lower Gleason score tumours or a longer PSA-DT. AWS after deferred CAB is uncommon.