Agreement of Gleason Score on Prostate Biopsy and Radical Prostatectomy Specimen: Is There Improvement With Increased Number of Biopsy Cylinders and the 2005 Revised Gleason Scoring?

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Abstract

For prostate cancer diagnoses we simultaneously incorporated the 2005 modified Gleason score (GS) and increased the standard number of biopsy cylinders to 8 to 12. This provided better Gleason score concordance between biopsy and radical prostatectomy (RP) specimens (n = 193) than before this change of practice (n = 135), although concordance rate (54%) remained rather poor. More tumors are labeled intermediate-/high-grade using the modified Gleason score.

Introduction:

The objectives of this study were to assess the agreement of GS on biopsy compared with RP specimens and to assess whether an increased number of biopsy cylinders and the 2005 International Society of Urological Pathology (ISUP) GS modification improved this agreement.

Materials and Methods:

Pathological data of biopsy and RP specimens were analyzed in 328 consecutive patients, before (group 1; n = 135) and after (group 2; n = 193) implementation of the 2005 ISUP modification. Additionally, patients had more biopsy cylinders taken in group 2 (mean 10 vs. 6.9). The agreement of GS between biopsy and RP specimens was evaluated using the kappa coefficient. GS was pooled into 3 grades: low- (GS ≤ 6), intermediate- (GS = 7), and high-grade (GS ≥ 8) prostate cancer.

Results:

Kappa coefficient for GS in group 1 and 2 was 0.261 and 0.341, respectively. For tumor grade, this was 0.308 and 0.359 for group 1 and 2, respectively. For RP specimens, there was more agreement between biopsy and RP GS in group 2 compared with group 1 (53.9% vs. 37.8%). Upgrading was almost exclusively (89.5%) seen in patients with biopsy GS ≤ 6 and was lower in group 2 (25.4% vs. 48.1%) because of classification of more intermediate- and high-grade tumors using the 2005 ISUP modification. Taking > 6 biopsy cylinders was associated with better GS and tumor grade agreement.

Conclusion:

Extended biopsy template and the 2005 ISUP modification resulted in an improved agreement between biopsy GS and RP GS and a shift toward more aggressive tumors.

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