Value of Prostate Specific Antigen Density and Percent Free Prostate Specific Antigen for Prostate Cancer Prognosis

Purpose: Limited data exist on the relationship of percent free prostate specific antigen and prostate specific antigen density with prostate cancer prognosis. Therefore, we compared percent free prostate specific antigen and prostate specific antigen density with prostate specific antigen, Gleason sum and stage to predict prostate cancer prognosis in a large cohort using a single prostate specific antigen and free prostate specific antigen assay. Materials and Methods: Between 1999 and 2007 a total of 1,656 patients with prostate cancer underwent laparoscopic radical prostatectomy at the Charite Berlin. There were 322 patients excluded from analysis for a variety of reasons. The final 1,334 patients had prostate specific antigen, free prostate specific antigen, prostate volume and complete pathological analysis available. Results: Median followup was 60.3 months (range 0.2 to 135). Median age (63 years, range 43 to 75) did not differ between the 1,092 patients without and the 242 with biochemical recurrence (p = 0.956), but prostate volume, prostate specific antigen and percent free prostate specific antigen differed significantly (p < 0.0001). While prostate specific antigen and prostate specific antigen density increased significantly in patients with Gleason less than 7, 7 and greater than 7 tumors, percent free prostate specific antigen decreased significantly (p <0.0001). Prostate specific antigen, percent free prostate specific antigen and prostate specific antigen density differed significantly between pT2 and pT3 tumors, and between patients with vs without positive surgical margins. On univariate analysis Gleason sum, pathological stage, positive surgical margin, total prostate specific antigen, percent free prostate specific antigen and prostate specific antigen density were predictors of biochemical recurrence-free survival. Multivariate Cox regression analysis identified Gleason sum, pathological stage, positive surgical margin and prostate specific antigen density as independent predictors of biochemical recurrence-free survival, while percent free prostate specific antigen and total prostate specific antigen failed to be significant. Conclusions: Few models for prostate cancer prognosis include prostate specific antigen density. There is substantial value in prostate specific antigen density but not in percent free prostate specific antigen for improving prostate cancer prognosis and biochemical recurrence prediction.