Prostate-specific antigen kinetic profiles during androgen deprivation therapy as prognostic factors in castration-resistant prostate cancer

Objective: To identify pretreatment prognostic factors for patients with castration-resistant prostate cancer (CRPC) undergoing docetaxel (DCT) chemotherapy. Materials and methods: We retrospectively analyzed 102 patients with CRPC who underwent DCT chemotherapy (dosage: 60-75mg/m²) from December 2001 to August 2013. The parameters evaluated as prognostic factors were as follows: age, body mass index, Gleason score, clinical TNM stage, prior radical prostatectomy, prior radiation therapy, performance status, presence of pain, laboratory results at the start of DCT, and prostate-specific antigen (PSA) kinetics during prior androgen deprivation therapy (ADT), including PSA level at the start of ADT (PSA-ADT), PSA half-time (PSAT_1/2), time to nadir, PSA level at nadir (PSA-Nadir), duration of nadir, PSA doubling time (PSADT), and PSA level at the start of DCT (PSA-DCT). Univariate and multivariate analyses were performed to identify independent prognostic factors. Results: Median cancer-specific survival (CSS) duration following CRPC diagnosis was 28.0 months. In univariate analyses, performance status, serum albumin, serum creatinine, PSAT_1/2, time to nadir, PSA-Nadir, duration of nadir, PSADT, and PSA-DCT showed a potential association with prognosis (P<0.001-0.077). Multivariate analyses of these parameters showed that performance status (hazard ratio [HR] = 0.046; P = 0.046), serum creatinine (HR = 3.028; P = 0.036), PSAT_1/2 (HR = 0.172; P = 0.007), PSA-Nadir (HR = 4.884; P = 0.033), PSADT (HR = 0.148; P<0.001), and PSA-DCT (HR = 5.222; P = 0.004) remained independent predictors of CSS in CRPC. Conclusions: PSA kinetic parameters measured during prior ADT are significant surrogate markers predicting CSS in patients undergoing DCT chemotherapy for CRPC.