Rapidly decreasing level of prostate-specific antigen during initial androgen deprivation therapy is a risk factor for early progression to castration-resistant prostate cancer: A retrospective study

To build a practical model for predicting the progression to castration-resistant prostate cancer (CRPC) after androgen deprivation therapy (ADT). In all, 185 patients with prostate cancer who had received ADT as the primary therapy at our institution, from 2003 to 2014, were retrospectively enrolled. The following clinical variables were included in the analysis: age, clinical tumor, node, metastasis stage, Gleason score, risk groups of prostate cancer, prostate-specific antigen (PSA) at the initiation of ADT, PSA nadir after ADT, velocity of PSA decline, and the time to PSA nadir. Cox proportional-hazards regression models were calculated to estimate effects of these variables on the time of progression to CRPC. On univariate and multivariate analyses, the presence of distant metastasis before ADT (hazard ratio [HR] 6.030, 95% confidence interval (CI) 3.229-11.263, P=.001), higher PSA nadir (HR 1.185, 95% CI 1.080-1.301, P=.001), a velocity of PSA decline >11ng/mL per month (HR 2.124, 95% CI 1.195-3.750, P=.001), and a time to PSA nadir <= 9 months (HR 0.276, 95% CI 0.162-0.469, P=.004) were significantly associated with an increased risk of progression to CRPC. Patients with a rapidly decreasing PSA level in the initial phase of ADT are more likely to progress to CRPC. Our findings provide a practical approach to screen patients during ADT for early identification of those likely to progress to CRPC, allowing treatment to be modified to improve outcomes.