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BACKGROUND: Preoperative clinical staging, PSA, and Gleason score, both alone and in combination, predict margin status and biochemical recurrence. Current convention mandates the highest Gleason score of all biopsies determines the preoperative Gleason score. We compared standard Gleason score to a weighted Gleason score to determine which better predicted margin status and biochemical recurrence.
METHODS: Using an IRB approved prospectively maintained database, 433 consecutive robotic radical prostatectomies performed by a single surgeon between January 1, 2007 and December 31, 2008 were selected. Specimens were whole mounted, sectioned at 3 mm intervals with the apex and base being additionally sectioned at right angles. Any tumor at the inked margin was considered a positive margin. The percent tumor involvement for each core was used to weigh each individual core's Gleason toward a weighted Gleason score. This score and a rounded (more clinically useful) version were compared to the standard Gleason score. Recurrence was defined as a confirmed PSA of 0.2 or greater or the institution of salvage therapy. The standard, weighted, and rounded weighted clinical Gleason scores were correlated with pathologic Gleason score, positive margin rates, and recurrence rates using Spearman, point by serial, or Cramer’s V correlation as appropriate for respective level of data.
RESULTS: Of the 433 consecutive cases, 257 were Gleason 6 with uniform cores. Of the 176 cases with clinical Gleason ≥ 7, 10 cases had insufficient data leaving 166 for analysis. 89 had no discrepancy in Gleason score between cores while 77 had non uniform Gleason scores on individual cores. Median follow-up was 60 months. The positive margin rate was 30%. The recurrence free rate was 78.3%. The standard clinical Gleason score predicted pathologic Gleason score (.614) significantly better than clinical weighted (.461) or clinical rounded weighted Gleason score (.497), (p=.05). There were no significant differences in the ability of standard, weighted, and rounded weighted clinical Gleason scores to predict margin status or clinical recurrence. Of the three methods, though not statistically significant, standard clinical Gleason score performed best.
CONCLUSIONS: In situations where there are varying Gleason scores in different biopsies, a weighted clinical Gleason score is not a better predictor of positive margin and recurrence rates than standard Gleason score. The current convention of using the highest Gleason score of all cores to determine preoperative Gleason score should continue.