title: Gleason scoring: a comparison of classical and modified (international society of urological pathology) criteria using nadir PSA as a clinical end point.
abstract: OBJECTIVE
  To compare the distribution and predictive performance of Gleason grade and scores derived using classical and modified (International Society of Urological Pathology) criteria.
  
  
  METHODS
  Classical and modified Gleason grades and scores were assigned to cases of prostate carcinoma accessioned by the Trans-Tasman Radiation Oncology Group RADAR trial. Separate scores were derived for each grading system based on the percentage of each Gleason grade per case (area-based score) and the score of the highest scoring core. The predictive performance of each of the four Gleason scores assigned to each case was evaluated using nadir prostate specific antigen (nPSA) as a clinical end point.
  
  
  RESULTS
  Modified Gleason scoring resulted in an upward shift of scores, primarily resulting from the reclassification of classical pattern 3 to modified pattern 4. On re-grading classical Gleason score 7 cores, there was a 64% decrease in the number of cores with < 25% Gleason pattern 4 tumour, while the number of cores with 75-100% Gleason pattern 4 tumour increased by 96%. All four scoring models performed reasonably well as predictors of nPSA; however, on comparison of the prognostic gradients of the grade groupings, classical Gleason scoring outperformed modified Gleason scoring.
  
  
  CONCLUSIONS
  The overlap of the predictive performance of Gleason pattern 3 with Gleason pattern 4, suggests that review of the defining features of modified pattern 4 may improve the prognostic prediction of modified Gleason scoring.
authors.affiliation: Department of Pathology and Molecular Medicine, Wellington School of Medicine and Heath Sciences, University of Otago, Wellington, New Zealand. bd@wnmeds.ac.nz
authors.forename: Brett
authors.initials: B
authors.lastname: Delahunt
authors.forename: David S
authors.initials: DS
authors.lastname: Lamb
authors.forename: John R
authors.initials: JR
authors.lastname: Srigley
authors.forename: Judy D
authors.initials: JD
authors.lastname: Murray
authors.forename: Chantelle
authors.initials: C
authors.lastname: Wilcox
authors.forename: Hemamali
authors.initials: H
authors.lastname: Samaratunga
authors.forename: Christopher
authors.initials: C
authors.lastname: Atkinson
authors.forename: Nigel A
authors.initials: NA
authors.lastname: Spry
authors.forename: David
authors.initials: D
authors.lastname: Joseph
authors.forename: James W
authors.initials: JW
authors.lastname: Denham
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000473:pathology*; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging / Q000379:methods*; D017410:Practice Guidelines as Topic; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology* / Q000601:surgery; D012372:ROC Curve
chemical_list: D017430:Prostate-Specific Antigen