The effect of modified Gleason grading on the score concordance between the Gleason scores of needle biopsy and radical prostatectomy specimens in prostatic carcinoma

Objective: The aim of this study was to evaluate the effect of modified Gleason grading, recommended at International Society of Urological Pathology Consensus Conference in 2005, on the concordance of Gleason scores between prostatic needle biopsy and radical prostatectomy specimens. Materials and methods: A total of 71 needle biopsy and radical prostatectomy specimens obtained from patients who underwent prostatectomy in our hospital between 2005 and 2008 were regraded with conventional and modified Gleason grading. The Gleason scores of the prostatic needle biopsy and radical prostatectomy specimens, which were achieved by conventional Gleason grading, were statistically compared with those of modified Gleason grading. Then, the concordance between the Gleason scores of needle biopsy and radical prostatectomy specimens were estimated separately by conventional and modified Gleason grading, and compared statistically. Results: When the conventional and modified Gleason scores of 71 patients were compared, a new Gleason score was achieved in 30 out of 71 needle biopsies (42.3%) (p<0.001) and in 10 out of 71 radical prostatectomy specimens (14.1%) (p=0.019). The concordance between needle biopsy and radical prostatectomy specimens improved from 32.4% to 46.5% (p=0.021). While a higher score was reported in 52.1% (37/71) of the cases in radical prostatectomy specimens, a lower score was reported in 15.5% (11/71) of the cases with conventional Gleason grading. The rates of overgrading and undergrading were respectively 42.2% (30/71) and 11.3% (8/71) in radical prostatectomy specimens with modified Gleason grading. Conclusion: The concordance between Gleason scores of prostatic needle biopsy and radical prostatectomy specimens improves, and the rate of undergrading and overgrading decreases with modified Gleason grading.