Alternation of non-steroidal antiandrogens for progressive prostate cancer following maximum androgen blockade - Results of non-steroidal antiandrogen sequential alternation for prostate cancer (NASA-PC) study group

Prostate cancer is an androgen-dependent tumor and initially responds well to hormone therapy. However, objective and biochemical progression generally ensue following successful hormone therapy, especially in patients with advanced prostate cancer. Cancer in this stage is described as hormone-refractory prostate cancer. Even at this stage, a subset of prostate cancer cells can still be hormonally dependent. For patients with androgen-independent but hormone-sensitive cancer cells, secondary hormone manipulation is active and can be expected to improve the prognosis. We herein report the results of sequential use of non-steroidal antiandrogens for patients with progression following first-line maximum androgen blockade (MAB) and we review the literature. Retrospective analysis was carried out for 232 patients with advanced prostate cancer (stages C and D) who received alternation of non-steroidal antiandrogens after progression following first-line MAB. A greater than 50% decrease in PSA was observed in 34.2% and 43.6% by switching from bicalutamide to flutamide and from flutamide to bicalutamide, respectively. As a whole, in 35.8% (83/232), PSA decreased by more than 50%. Some decrease in PSA was observed in 61.2% and those responders showed significantly better survival than the non-responders. The duration of the response to the second-line MAB was more than 202 days. The patients who received alternation of antiandrogens before the level of PSA rose to 4.0 ng/ml showed a better response to the second-line therapy. Both the present study and previous reports demonstrate that the response rates to the alternation of antiandrogens are 20-50% and this indicates that alternative antiandrogens offer some benefit for patients with relapse following first-line MAB. (Nishinihon J. Urol. 71: 3-10,2009).