Preoperative prediction of Gleason grade in radical prostatectomy specimens: the influence of different Gleason grades from multiple positive biopsy sites

Abstract

The Gleason score of prostate adenocarcinomas is an important preoperative predictor of cancer behavior, and is used to help guide treatment. In the setting of more than two positive biopsy sites, pathologists usually grade the tumor at each site separately, and the Gleason score may differ from each positive site. This study seeks to determine if the highest Gleason score in all biopsy sites, or the Gleason score in the site with the highest tumor volume on the needle biopsy is the best predictor of final Gleason score in the radical prostatectomy specimens. Various preoperative biopsy findings were analyzed. All 151 patients had at least two positive biopsy sites and underwent radical prostatectomy. Primary and secondary Gleason pattern grades were assigned for each positive biopsy site. The tumor volume in the needle biopsy site was defined by the percentage of areas of biopsy cores involved by cancer. The radical prostatectomy specimens were completely embedded and processed in the whole-mount method. The Gleason score from both the biopsy site with the highest Gleason score and the biopsy site with the highest tumor volume on the needle biopsy correlated equally well with final Gleason score at radical prostatectomy (Spearman correlation coefficient =0.54 for both, P<0.001). The Gleason score from both the biopsy site with the highest Gleason score and the biopsy site with the highest tumor volume on the needle biopsy also correlated with primary Gleason pattern grade at radical prostatectomy (Spearman correlation coefficient =0.53 for both, P<0.001). Secondary Gleason pattern grade from the biopsy site with the highest tumor volume on the needle biopsy correlated with secondary Gleason pattern grade at radical prostatectomy slightly better than those from the biopsy site with the highest Gleason score (Spearman correlation coefficient, 0.32 vs 0.24; both P<0.001). Our data indicate that the highest Gleason score from all sites and the Gleason score from the site with the highest tumor volume on the needle biopsy are equally and significantly predictive of final Gleason score on radical prostatectomy. Both methods of prediction are significantly predictive of primary and secondary Gleason pattern grade on radical prostatectomy. We recommend that the highest Gleason score from all positive biopsy sites should be used when assigning an initial score using needle biopsies.