[806] Gleason Grading Reproducibility Highlights Problematic Patterns for Differentiating Gleason Grade 3 Versus Gleason Grade 4: Implications for Active Surveillance Patients

Michael Bonham, Sarah Hawley, Lakshmi P Kunju, Dean Troyer, Ladan Fazili, Edward Jones, Marlo Nicholas, Jesse McKenney, Lawrence True, Jeff Simko. University of California, San Francisco, San Francisco, CA; Stanford University Medical Center, Palo Alto, CA; University of Michigan, Ann Arbor, MI; Eastern Virginia Medical School, Norfolk, VA; University of British Columbia, Vancouver; University of Texas Health Science Center at San Antonio, San Antonio, TX; University of Washington, Seattle

Background: Active Surveillance (AS) is becoming a more accepted management strategy for patients with prostate cancers that have low risk of progression. Most of the AS management protocols rely heavily on the Gleason score obtained from serial biopsies; scores of 7 or higher trigger a recommendation for primary treatment with curative intent. This places heavy emphasis on discriminating between Gleason patterns 3 and 4. We have instituted a rapid biopsy review program within a multi-institutional clinical trial to evaluate variability & to guide standardization among participating pathologists for cases that are borderline between patterns 3 and 4.
Design: Digital images from 27 cases were reviewed by 7 participating prostate pathologists. For each case, at least two images (100X and 200X magnification) were circulated.
Results: Agreement was unanimous (7/7 pathologists) in 2 of 27 cases. Five pathologists agreed on the score in 16 cases. Of these 16 cases, 2 were scored as 6, 13 as 7, and one as tertiary pattern 5. In 11 cases pathologists assigned ≥3 Gleason scores; in 3 cases 4 or more Gleason scores were assigned. Fewer than 5 pathologists agreed on the score of Gleason 6 vs. 7 in 33% of cases. The percentage of cases for which a Gleason score 6 was assigned by an individual pathologist ranged from 11% to 60%. Of cases with marked grading variance, 6 consisted of small, tightly packed glands, making identification of a cribriform architecture difficult; 3 consisted of small, angulated, poorly-formed glands, which is a morphology poorly defined by the ISUP 2005 Gleason grading criteria.
Conclusions: The presence of Gleason grade 4 is a threshold event for more aggressive treatment in active surveillance patients. In the present study the prostate pathologists did not reach a consensus as to whether pattern 4 was present in 33% of the cases. The difficulties in delineating this important treatment threshold include the definition of cribriform growth among crowded glands and classification of poorly-formed single glands.
Category: Genitourinary (including renal tumors)

Wednesday, March 21, 2012 9:30 AM

Poster Session V # 120, Wednesday Morning

 

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