Prognostic and Predictive Factors for Anti-androgen Withdrawal in Castration-resistant Prostate Cancer

Background/Aim: We aimed to identify prognostic and predictive factors for anti-androgen withdrawal syndrome (AWS) to help guide decisions on anti-androgen withdrawal in castration-resistant prostate cancer (CRPC). Patients and Methods: This study included 95 patients with prostate cancer which progressed to CRPC despite primary androgen-deprivation therapy (ADT). AWS was defined as >50% prostate-specific antigen decline after anti-androgen withdrawal. Associations between AWS, and clinicopathological factors and prognosis were investigated. Results: Among the 95 patients, 84 (88.4%) underwent anti-androgen withdrawal, among whom AWS was recognized in nine (10.8%). Gleason score and response duration to primary ADT were predictors of AWS. Long duration of response to primary ADT was also associated with better progression free survival [hazard ratio (HR)=0.021, 95% confidence interval (CI)=0.0025-0.14, p<0.0001 and overall survival (HR=0.0042, 95% CI=0.0001-0.089, p<0.0001). Age (HR=7.19, 95% CI=1.08-54.27, p=0.041) and radiological/ clinical progression (HR=3 .14, 95% CI=1.35-6 .43, p=0.010) were associated with worse overall survival. Intriguingly, radiological/clinical progression was associated with the differential effect of anti-androgen withdrawal on overall survival (interaction p=0.031). Conclusion: Patients who suffer radiological/clinical progression are unsuitable candidates for anti-androgen withdrawal.