title: Prostate cancers scored as Gleason 6 on prostate biopsy are frequently Gleason 7 tumors at radical prostatectomy: implication on outcome.
abstract: OBJECTIVE
  Differentiation between Gleason score 6 and 7 in prostate biopsy is important for treatment decision making. Nevertheless, under grading errors compared with the actual pathological grade at radical prostatectomy are common. We compared the characteristics and outcomes of tumors that were scored 6 on prostate biopsy but were 7 on subsequent radical prostatectomy pathological evaluation to those in tumors with a consistent rating of Gleason score 6 or 7 at biopsy and surgery.
  
  
  METHODS
  We performed a retrospective database analysis from our referral center (1989 to 2004). We compared pre-prostatectomy characteristics, radical prostatectomy pathological features and the post-radical prostatectomy prostate specific antigen failure rate, defined as any 2 consecutive detectable prostate specific antigen measurements, in 3 subgroups of patients, including 156 with matched Gleason score 6 in the prostate biopsy and radical prostatectomy, 205 with upgraded Gleason score 6/7, that is prostate biopsy Gleason score 6 and radical prostatectomy Gleason score 7, and 412 with matched Gleason score 7 in the prostate biopsy and radical prostatectomy.
  
  
  RESULTS
  Radical prostatectomy Gleason score matched the prostate biopsy score in 38.2% of biopsy Gleason score 6 and 81.4% of biopsy Gleason score 7 cases. Higher prostate specific antigen was associated and an increased percent of cancer in the prostate biopsy was predictive of discordance between the prostate biopsy and radical prostatectomy Gleason scores (p <0.001). Margin (p = 0.0075) or seminal vesicle involvement (p = 0.0002), cancer volume (p <0.001) and the prostate specific antigen failures rate (p = 0.014) were significantly higher in under graded Gleason score 7 cancer compared to those in matched Gleason score 6 cases. However, they were comparable to those with a matched Gleason score 7 tumor grade (p = 0.66).
  
  
  CONCLUSIONS
  Almost half of tumors graded Gleason score 6 at biopsy are Gleason score 7 at surgery. Upgraded Gleason score 6 to 7 tumors have outcomes similar to those of genuine Gleason score 7 cancer. For prostate biopsy Gleason score 6 tumors clinicians should consider the overall likelihood of tumor upgrading as well as specific patient characteristics, such as prostate specific antigen and the percent of tumor in the prostate biopsy, when contemplating treatments that are optimized for low grade tumors, including watchful waiting or brachytherapy.
authors.affiliation: Prostate Cancer Center, Princess Margaret Hospital, 620 University Avenue, Toronto, Ontario M5G 2M9, Canada.
authors.forename: Jehonathan H
authors.initials: JH
authors.lastname: Pinthus
authors.forename: Maciej
authors.initials: M
authors.lastname: Witkos
authors.forename: N E
authors.initials: NE
authors.lastname: Fleshner
authors.forename: Joan
authors.initials: J
authors.lastname: Sweet
authors.forename: Andrew
authors.initials: A
authors.lastname: Evans
authors.forename: M A
authors.initials: MA
authors.lastname: Jewett
authors.forename: Murray
authors.initials: M
authors.lastname: Krahn
authors.forename: Shabir
authors.initials: S
authors.lastname: Alibhai
authors.forename: John
authors.initials: J
authors.lastname: Trachtenberg
mesh_terms: D001706:Biopsy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000145:classification* / Q000473:pathology* / Q000601:surgery; D012189:Retrospective Studies