Impact of initial time to prostate-specific antigen nadir on survival in prostate cancer with bone metastasis initially treated with maximum androgen blockade therapy

Abstract

Background: The objective of this study is to provide certain data on clinical outcomes and their predictors of traditional maximum androgen blockade (MAB) in prostate cancer with bone metastasis. Methods: Subjects were patients with prostate adenocarcinoma with bone metastasis initiated to treat with MAB as a primary treatment without any local therapy at our hospital between January 2003 and December 2010. Time to prostate specific antigen (PSA) progression, overall survival (OS) time, and association of clinical factors and outcomes were retrospectively evaluated. Results: A total of 57 patients were evaluable. The median age was 70 years. The median primary PSA was 203 ng/ml. Luteinizing hormone-releasing hormone agonists had been administered in 96.5% of the patients. Bicalutamide had been chosen in 89.4 % of the patients as the initial antiandrogen. The median time to PSA progression with MAB was 11.3 months (95% confidence interval [CI], 10.4 to 13.0). The median OS was 47.3 months (95% CI, 30.7 to 81.0). Gleason score 9 or greater, decline of PSA level equal to or higher than 1.0 ng/ml with MAB, and time to PSA nadir equal to or shorter than six months after initiation of MAB were independent risk factors for time to PSA progression (P0.010, P0.005, and P0.001; respectively). Time to PSA nadir longer than six months was the only independent predictor for longer OS (HR, 0.255 [95% CI, 0.109 to 0.597]; P0.002). Conclusions: Initial time to PSA nadir should be emphasized for clinical outcome analyses in future studies on prostate cancer with bone metastasis.