Prostate Specific Antigen Half-Time and Prostate Specific Antigen Doubling Time as Predictors of Response to Androgen Deprivation Therapy for Metastatic Prostate Cancer

Abstract

We determined the clinical significance of prostate specific antigen half-time and prostate specific antigen doubling time after the prostate specific antigen nadir as predictors of the response to androgen deprivation therapy for metastatic prostate cancer. A total of 131 patients with metastatic prostate cancer treated with androgen deprivation were included in this analysis. Clinicopathological features and cancer specific survival were compared among the patients who were divided according to prostate specific antigen half-time and prostate specific antigen doubling time after the prostate specific antigen nadir. Median followup was 53.0 months. Baseline and nadir prostate specific antigen did not differ between the patients with a short prostate specific antigen half-time (1 month or less) and those with a long prostate specific antigen half-time (longer than 1 month). Patients with a short prostate specific antigen half-time had a higher Gleason score, shorter nadir duration and shorter cancer specific survival. No differences were found between the patients with a short (6 months or less) and those with a long (longer than 6 months) prostate specific antigen doubling time after the prostate specific antigen nadir in terms of baseline prostate specific antigen, nadir prostate specific antigen, biopsy Gleason score and prostate specific antigen half-time. A short prostate specific antigen doubling time after the prostate specific antigen nadir was associated with shorter nadir duration and poorer median cancer specific survival. On multivariate analysis Gleason score, nadir prostate specific antigen and prostate specific antigen half-time remained independent predictors of an increase in prostate specific antigen after androgen deprivation therapy. Nadir prostate specific antigen, prostate specific antigen half-time and prostate specific antigen doubling time after the prostate specific antigen nadir were prognostic factors for cancer specific survival. The results of our study suggest that prostate specific antigen half-time and prostate specific antigen doubling time after the prostate specific antigen nadir are independent prognostic indicators for an increase in prostate specific antigen after androgen deprivation therapy and cancer related death in patients with metastatic prostate cancer treated with androgen deprivation.