Prediction of potentially insignificant prostate cancer in men undergoing radical prostatectomy for clinically organ-confined disease

BACKGROUND: The objectives of the present study were to characterize, according to tumor significance, the clinicopathological features of patients with prostate cancer who underwent radical prostatectomy, and to determine useful parameters for predicting insignificant disease before surgery. METHODS: In this series, we included 195 patients who underwent radical prostatectomy for clinically organ-confined prostate cancer at our institution between January 1999 and November 2003. Several clinicopathological factors were analyzed, focusing on whether the largest tumor volume in radical prostatectomy specimens was >/=0.5 cm(3) or <0.5 cm(3), which is the criterion defined to distinguish insignificant cancer from significant cancer. RESULTS: Potentially insignificant cancer was detected in 28 of 195 patients (14.4%). There were significant differences between patients with insignificant disease and those with significant disease in serum prostate specific antigen (PSA) as well as all biopsy parameters, with the exception of biopsy Gleason score. Furthermore, final pathological examination demonstrated that these two patient groups showed significant differences in Gleason score and the incidence of extraprostatic disease extension. Pearson's correlation analysis showed that tumor volume in the prostatectomy specimens was significantly associated with serum PSA and all biopsy parameters; however, each of the correlations was comparatively weak. There was no single parameter that could viewed as a useful predictor of tumor significance. The best model for predicting insignificant tumor was the combined use of biopsy Gleason score <7 and percent of positive biopsy core (PPBC) <15%; however, the further addition of serum PSA <10 ng/mL to these two parameters failed to enhance the predictive value of cancer significance. CONCLUSIONS: These findings indicate that clinicopathological findings suggesting favorable features are well observed in patients with potentially insignificant prostate cancer compared to those with significant prostate cancer, and the combination of a biopsy Gleason score <7 and PPBC <15% might be useful as a predictor of insignificant disease.