Combined Prostate-specific Antigen Density and Biopsy Features to Predict "Clinically Insignificant" Prostate Cancer

Objectives: Prior studies have reported that men with a PSA density (PSAD) less than 0.15, less than 3 positive biopsy cores, 50% or less of any core involved, and a Gleason score 6 or lower are likely to have "insignificant" prostate cancer (CaP) in their radical prostatectomy (RRP) specimen. In this study, we examined the ability of PSAD and biopsy features to predict pathologic outcomes in a contemporary RRP population. Methods: From 1999 to 2005, 274 men underwent RRP and had the required data for our analysis. As our database does not record the percentage or length of cancer in each biopsy core, we examined the relative importance of PSAD, the number of positive biopsy cores, and Gleason grade to predict "insignificant" cancer, defined as organ-confined with a tumor volume less than 0.5 mL and no Gleason pattern 4 or 5. Results: Overall, by these criteria, 24.5% of patients were considered to have potentially "insignificant" cancer preoperatively; whereas, only 2.6% had a so-called "insignificant" tumor in the RRP specimen. Without the percentage of biopsy core involvement, the preoperative model to predict "insignificant" cancer was associated with 57% sensitivity, 76% specificity, 6% positive predictive value, and 99% negative predictive value. Conclusions: A model including Gleason grade, PSAD, and number of positive biopsy cores did not provide an accurate means of selecting patients for active monitoring in our patient cohort. However, it was helpful in identifying men with a high likelihood of "clinically significant" CaP. Knowledge of the percentage of biopsy core involvement with cancer may be a critical prognostic factor.