Is biopsy Gleason sum an independent predictor of biochemical progression following radical prostatectomy after adjusting for the pathological Gleason sum?

Abstract

4652 Background: Biopsy Gleason sum is a known important predictor of PSA failure following radical prostatectomy (RP). However, it is unclear whether it remains predictive of outcome after surgery when the pathological Gleason sum is known. Methods: We determined the association between biopsy Gleason sum and biochemical progression after correcting for both pre-operative and post-operative characteristics including pathological Gleason sum among 1,931 men treated with RP between 1988 and 2005 within the SEARCH Database. Gleason sum was examined as a categorical variable of 2–6, 3+4, and ≥4+3. Results: Higher biopsy Gleason sums were associated with increased prevalence of extra-capsular extension (p < 0.001), positive surgical margins (p < 0.001), seminal vesicle invasion (p < 0.001), positive lymph nodes (p < 0.001), and biochemical progression (log rank, p < 0.001). After adjusting for only pre-operative characteristics, both biopsy Gleason sums of 3+4 (p = 0.004) and ≥4+3 (p < 0.001) were associated with increased risk of biochemical progression when compared to biopsy Gleason sums of 6 or less. After further adjusting for multiple pathological characteristics including pathological Gleason sum, the association between higher biopsy Gleason sum and risk of progression was little changed in that men with biopsy Gleason sums of 3+4 (p = 0.001) and ≥4+3 (p < 0.001) were significantly more likely to progress. Furthermore, when stratified by pathological Gleason sum, higher biopsy Gleason sums were associated with increased risk of biochemical progression within each pathological Gleason sum category (log-rank, p ≤ 0.007). Conclusions: Biopsy Gleason sum remains a strong predictor of outcome even when the pathological Gleason sum is known. If confirmed at other centers, incorporation of biopsy Gleason sum into post-operative nomograms designed to predict risk of progression might improve model precision. No significant financial relationships to disclose.