NE-AUA 2006 Annual Meeting, September 28 - 30, 2006, The Westin Hotel & Rhode Island Convention Center Providence, Rhode Island
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Caution: Biopsy Gleason Sum May Confound Treatment Algorithms for Prostate Cancer
Michael Cohen, MD1, John Libertino, MD1, Robert Hanley, MD1, Robin Ruthazer, MS2, Karim Hamawy, MD1, Andrea Sorcini, MD1, Robert Roth, MD1, Ingolf Tuerk, MD, PhD1.
1Lahey Clinic Medical Center, Burlington, MA, USA, 2Tufts-New England Medical Center, Boston, MA,

Background: Biopsy Gleason sum is a critical variable that assists urologists in recommending therapeutic options for patients with newly diagnosed prostate cancer. Differences in the biopsy Gleason sum greatly affect treatment strategies from watchful waiting for low grade disease to non-surgical treatment for high grade disease. Therefore, we analyzed the accuracy of the prostate biopsy Gleason sum in 2,328 patients undergoing radical prostatectomy at our institution.
Methods: From 1983 to 2005, we maintained a prospective database on 2,816 patients undergoing radical prostatectomy at our institution. Patients were excluded who received preoperative hormones or who did not have a preoperative and post-operative Gleason sum available. Therefore, a total of 2,328 patients were included in this study. The biopsy and prostatectomy Gleason sum were separated into the following 4 grades: low (Gleason 2-4), mild (Gleason 5-6), moderate (Gleason 7), and high (Gleason 8-10). Statistical tests of symmetry, agreement, and Spearman rank correlation were performed.
Results: The prostatectomy grade increased in 90.1% of low, 48.4% of mild, and 19.9% of moderate grade biopsies and decreased in 35.5% of high grade biopsy specimens as shown in Figure 1. As the biopsy grade increased, the prostatectomy grade also increased (positive Spearman rank correlation = 0.44, p≤0.0001). However, the prostatectomy grade was significantly greater than the biopsy grade (Test of symmetry, p≤0.0001). Furthermore, the biopsy and prostatectomy grade agree more than expected by chance alone, but the value of the weighted Kappa statistic, as a measure of agreement, (Kappa=0.31: 95%CI (0.28, 0.34)) indicates only fair agreement between the biopsy and prostatectomy Gleason grade.

Conclusions: Overall, the biopsy Gleason grade inaccurately predicts the prostatectomy Gleason grade. Patients with a low (Gleason sum 2-4) or mild (Gleason sum 5-6) grade prostate biopsy likely have a more aggressive than predicted prostatectomy Gleason grade, and patients with a high grade prostate biopsy (Gleason sum 8-10) may likely have a less aggressive than predicted prostatectomy Gleason grade. The inability of the prostate biopsy to accurately predict the prostatectomy Gleason grade may require urologists to reexamine some clinical treatment algorithms for prostate cancer.


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