Purpose: Prostate specific antigen (PSA) is a useful marker for predicting outcomes following treatment for prostate cancer but, given the evolving nature of prostate cancer, there is an ongoing need to refine its use. We assessed preoperative PSA doubling time (PSADT) and PSA velocity (PSAV) as predictors of outcome following radical retropubic prostatectomy (RRP).
Materials and methods: We identified 2,290 men who were treated with RRP for prostate cancer between 1990 and 1999 with multiple preoperative PSA measurements available. PSADT was calculated by log linear regression and PSAV was calculated by linear regression. These parameters were used in preoperative and postoperative multivariate models for the end points of biochemical and clinical progression, and cancer death.
Results: At a median followup of 7.1 years (range 0.1 to 14.5) biochemical progression, clinical progression and death from prostate cancer were observed in 583, 156 and 42 patients, respectively. The HR for death from prostate cancer was 6.22 (95% CI 3.33 to 11.61) in men with PSADT less than 18 months vs 18 or greater and 6.54 (95% CI 3.51 to 12.19) in men with PSAV greater than 3.4 ng/ml yearly vs 3.4 or less. On multivariate analysis adjusting for preoperative or postoperative variables PSADT and PSAV remained significant predictors of each outcome. When assessed jointly, PSAV was significant as a predictor of biochemical progression, while PSADT was a significant predictor of clinical progression and cancer death.
Conclusions: This study confirms the usefulness of preoperative PSA kinetics for predicting post-RRP outcomes, which may be useful for stratifying patients, so that rational management decisions can be made with respect to observation, intervention and adjuvant treatment. While PSADT maybe biologically more accurate and stronger on multivariate analysis, PSAV is clinically easier to use and a good approximation in the short term.