Prostate specific antigen doubling time after radical prostatectomy: effect of neoadjuvant androgen deprivation therapy

Abstract

Purpose: We determined the predictors of prostate specific antigen (PSA) doubling time in patients with relapse after radical prostatectomy as well as whether PSA doubling time is shorter in those treated versus not treated with neoadjuvant androgen deprivation therapy.

Materials and methods: We calculated PSA doubling time in 204 patients with PSA relapse after radical prostatectomy who were or were not treated with neoadjuvant androgen deprivation therapy. Analysis of covariance was used to determine the effect of clinical and pathological parameters on PSA doubling time, and the proportion of variability explained by these parameters.

Results: Clinical stage, and combined clinical stage and margin status, clinical stage and androgen deprivation therapy status, androgen deprivation therapy status and time to PSA relapse, and androgen deprivation therapy status and pretreatment PSA were significant predictors of PSA doubling time. Any variable or combination of variables explained up to only 21% of PSA doubling time variability. When stratified by pretreatment PSA, clinical stage and biopsy grade, the difference in doubling times in patients treated with or without neoadjuvant androgen deprivation therapy was significant only for 4.1 to 10 ng./ml. PSA. In this group mean doubling time plus or minus standard deviation in patients receiving neoadjuvant androgen deprivation therapy and those treated only with radical prostatectomy was 7.6+/-1.0 and 15.4+/-2.6 months, respectively.

Conclusions: Our study indicates that it is difficult to predict PSA doubling time in an individual. The small proportion of variability in PSA doubling time explained by the interaction of androgen deprivation therapy status and other variables indicates that these factors are not clinically significant.