Gleason score concordance on biopsy-confirmed prostate cancer: is pathological re-evaluation necessary prior to radical prostatectomy?

Abstract

Objectives: • Gleason sum from prostate biopsy (bGS) is an important tool in classifying severity of disease, ultimately influencing clinical management. • Commonly, pathology specimens are re-evaluated internally prior to surgery. • We evaluate agreement of bGS with prostatectomy Gleason sum (pGS) and the impact of re-grading on prediction of true underlying tumor architecture.

Materials and methods: • Retrospective analysis of men who underwent robotic-assisted radical prostatectomy (RARP) by two surgeons from 2005-2009. Initial transrectal ultrasound (TRUS) biopsy demonstrated carcinoma at an outside lab. Specimens were re-evaluated by our GU pathologists prior to surgery. Biopsy data were correlated with pGS. • Kappa (κ) statistics for agreement and linear regression analyses were used for categorical variables. Coefficient of concordance was used for continuous variables.

Results: • 100 patients had 331 positive biopsies. Agreement (κ) for bGS between outside labs and our pathologists was 0.55 (p < 0.001). • Internal read was twice as likely to upgrade vs. downgrade outside bGS (23% vs. 11%). • When re-evaluation resulted in a change in bGS, agreement with pGS was κ= 0.29, vs. κ=-0.04 for agreement of initial (outside) bGS with pGS. • When no change was made to bGS, agreement with pGS was κ= 0.40 (p < 0.001).

Conclusion: • Good reproducibility seen between outside labs and our institution on bGS. Internal pathology re-reads correlated better with pGS than original community bGS. When re-reads result in a change in bGS, there is a marked improvement in prediction of underlying tumor architecture confirming the value of re-evaluating all external biopsies prior to definitive surgery.