Predicting disease recurrence in intermediate and high-risk patients undergoing radical prostatectomy using percent positive biopsies: results from CaPSURE

Abstract

Objectives. To determine whether percent positive biopsies could be used to predict the probability of disease recurrence in contemporary patients undergoing radical prostatectomy in community-based practice settings. Previous studies have demonstrated the importance of systematic prostate biopsy results in the risk assessment for newly diagnosed patients with prostate cancer. Methods. We studied 1265 patients enrolled in CaPSURE (a longitudinal registry of patients with prostate cancer) who underwent radical prostatectomy as definitive local treatment of their prostate cancer. Preoperative characteristics, including age, race, prostate-specific antigen (PSA) level at diagnosis, clinical T stage, biopsy Gleason score, and percent positive prostate biopsies at the time of diagnosis, were determined for each patient. Disease recurrence was defined as PSA level of 0.2 ng/mL or greater on two consecutive occasions after radical prostatectomy or the occurrence of a second cancer treatment more than 6 months after surgery. Cox proportional regression analysis was performed to determine the significant independent predictors of disease recurrence. Patients were assigned to previously described risk groups on the basis of clinical tumor stage, PSA at diagnosis, and biopsy Gleason score. The likelihood of disease recurrence for each risk group, stratified according to the percentage of positive biopsies (0% to 33%, 34% to 66%, and more than 66%), was determined using the Kaplan-Meier method and compared using the log-rank test. Results. The median follow-up was 3.3 years after surgery. The serum PSA level at diagnosis, biopsy Gleason score, percent positive biopsies, and ethnicity were significant independent predictors of disease recurrence. The percentage of positive prostate biopsies was a significant predictor of disease recurrence for low, intermediate, and high-risk patients. For patients with high-risk disease, the likelihood of disease recurrence 5 years after surgery was 24%, 34%, and 59% for patients with 0% to 33%, 34% to 66%, and more than 66% positive biopsies, respectively. Conclusions. Serum PSA, biopsy Gleason score, and percent positive biopsies were significant predictors of disease recurrence in this population. The percent positive biopsies may be useful in identifying high-risk patients suitable for definitive local therapy.