Usefulness Of The 2005 International Society Of Urologic Pathology Gleason Grading System In Prostate Biopsy And Radical Prostatectomy Specimens

Historically, the Gleason grading system was most commonly used for prostate cancer (CaP) pathologic analysis. In 2005, the International Society of Urologic Pathology (ISUP) Gleason Grading Consensus was proposed. The ISUP differs in that:

a) a Gleason score (GS) of <4 in biopsy tissue is rarely made

b) most cribriform patterns would be diagnosed as Gleason pattern 4 while rare cribriform patterns would be Gleason pattern 3

c) different GS used for biopsy and RP specimens, high-grade tumor of any quantity on biopsy should be included within the GS

d) for tertiary pattern on biopsy the primary pattern and highest grade should be recorded and in RP specimens when a different GS occurs in separate tumor nodule then a separate GS should be recorded.

This Japanese report evaluates the ISUP system for biochemical recurrence, and compares conventional GS (CGS)to ISUP GS (IGS) in biopsy and RP specimens.

The cohort consisted of 250 men with clinical stage T1-2 N0M0 CaP diagnosed between 1996 and 2006. All patients had TRUS with biopsy and RP. Of these men, 103 did not have neoadjuvant or adjuvant therapies and were eligible for this analysis. One uropathologist determined the IGS scoring. D'Amico risk stratification classified 34 men as low risk, 37 men as intermediate risk and 32 men as high risk.

The conventional CGS for the biopsy specimen was concordant with the RP in 64% of cases with undergrading in 28% and overgrading in 8%. The IGS was undergraded in 27% with slightly higher concordance (70%) than for CSG while overgrading was significantly lower (3%). There were no significant differences between CSG and IGS for RP specimens. By D'Amico categories, 10 of 34 (29%) classified as low risk on IGS were intermediate risk according to CGS. Five (14%) and four (11%) of the 37 intermediate risk based on CGS were low and high risk respectively, by IGS. However, there were no statistically significant differences between CGS and IGS for D'Amico stratification. Also, no differences in pathological staging between CGS and IGS were statistically significant. Biochemical recurrence-free survival (BRFS) in men with biopsy specimens classified by CGS did not differ among GS groups (<6, 7 and >8), however when IGS was applied to the biopsy specimens there was a significant difference in BRFS among the 3 groups. Also, the BRFS in RP specimens classified by GS groups (<6, 7 and >8) by CGS were not different. However, application of IGS to the biopsy demonstrated BRFS differed significantly among the 3 groups. This suggests that application of the IGS to the prostate biopsy specimen more closely correlates with BRFS.

Uemura H, Hoshino K, Sasaki T, Miyoshi Y, Ishiguro H, Inayama Y, Kubota Y
BJU Int. 2008 Dec 5. Epub ahead of print.
doi:10.1111/j.1464-410X.2008.08197.x