Gleason group concordance between biopsy and radical prostatectomy specimens: A cohort study from Prostate Cancer Outcome Registry - Victoria

Background: A new prostate cancer (PCa) prognostic grading system [Gleason groups (GGs)] has been proposed based on the contemporary Gleason scores (GSs), which has five simplified prognostic categories. The objective of this study was to evaluate the agreement between the GGs of prostate biopsy and radical prostatectomy specimens and to identify predictive factors for upgrading GGs.

Methods: A total of 5339 cases of RP notified to the Prostate Cancer Outcomes Registry, Victoria, Australia over 6 years (2009-2014) from 46 hospitals, were included. The upgrading was evaluated using the new PCa prognostic grading system, the International Society of Urologic Pathology grade groups, which has five prognostic categories. GG 1 is GS ≤ 6, GG 2 is GS 3 + 4 = 7, GG 3 is GS 4 + 3 = 7, GG 4 is GS 8, and GG 5 is GS 9 and 10. Predictors of upgrading were assessed using univariate and multivariate models.

Results: The GG of prostate biopsies and RP specimens were concordant in 54.5% of cases, while 31.1% were upgraded and 14.3% were downgraded. Longer time interval between biopsy and RP [44-99 days: odds ratio (OR) = 1.3, 95% confidence interval (CI) = 1.1-1.6; > 99 days: OR = 3.0, 95% CI = 2.4-3.8), and RP performed in a metropolitan hospital (biopsy in a regional hospital: OR = 2.2, 95% CI = 1.6-3.2, biopsy in a metropolitan hospital: OR = 1.7, 95% CI = 1.2-2.2) were significant predictors of GG upgrading. Patients who were diagnosed by transperineal biopsy compared to transrectal ultrasound (OR = 0.6, 95% CI = 0.5-0.8) and higher percentage of positive biopsy cassettes (25-62.5%: OR = 0.7, 95% CI = 0.6-0.8, > 62.5: OR = 0.6, 95% CI = 0.5-0.8) were significantly associated with less likelihood of upgrade.

Conclusion: The lack of concordance among hospitals may be attributable to the specialist expertise of the pathologist. Expert review of specimens may help to overcome this discordance. Clinicians should consider clinical parameters and potential limitations of the GG at biopsy when making treatment decisions with regard to PCa.