Is there a difference in outcome after radical prostatectomy between patients with biopsy Gleason sums 4, 5, and 6? Results from the SEARCH database.

PURPOSE

Fewer patients newly diagnosed with prostate cancer today have biopsy Gleason sums <6 compared to several years ago. Several tables and nomograms for predicting disease recurrence after definitive therapy provide little or no discrimination between biopsy Gleason sums 4, 5, and 6. We sought to examine the significance of biopsy Gleason sum for predicting biochemical failure following radical prostatectomy (RP) for men with biopsy Gleason sums of 4, 5, and 6.

MATERIALS AND METHODS

We examined data from 988 men treated with RP between 1988 and 2002 who had biopsy Gleason sums of 4-6. Clinical and pathological variables as well as outcome information were compared between men with biopsy Gleason sums of 4-6. The log-rank and Cox proportional hazards analysis were used to determine whether biopsy Gleason sum provided unique prognostic information for men with low biopsy Gleason sums undergoing RP.

RESULTS

There was statistically significant, but overall weak correlation between biopsy Gleason sum and Gleason sum of the RP specimen (Spearman's r=0.277, P<0.001). As biopsy Gleason sum increased from 4 to 5 to 6, there was a steady rise (HR=1.31 for each one point increase in Gleason sum, Cox's model) in the risk of PSA failure (P=0.025, log-rank). On multivariate analysis comparing biopsy Gleason sum, preoperative PSA, clinical stage, year of surgery, percent of biopsy cores positive, and age for their ability to predict time to biochemical recurrence, only PSA (HR 2.09, CI 1.56-2.80, P<0.001) and biopsy Gleason sum (HR 1.33, CI 1.05-1.70, P=0.019) were significant independent predictors of PSA failure.

CONCLUSIONS

Despite weak correlation between biopsy and pathologic Gleason sum among men with biopsy Gleason sum 4-6 tumors, grade was a significant independent predictor of PSA failure following RP. In the range of 4-6, biopsy Gleason sum acted as a continuous variable for predicting PSA failure. The routine use of Gleason sums 4 and 5 to grade prostate needle biopsy specimens should not be abandoned.