Gleason underestimation is predicted by prostate biopsy core length.

purposeTo evaluate whether core length impacts biopsy accuracy and Gleason score underestimation compared to radical prostatectomy (RP) specimens.

methodsFrom 2010 to 2011, 8,928 cores were trans-rectal obtained from 744 consecutive patients (178 RP, 24%), 557 by an experienced performer (>250/year) and 187 (25%) by in-training urology residents. Prospectively analyzed variables were core length, age, prostate volume, free and total prostate-specific antigen (PSA), PSA density and free/total PSA ratio.

resultsMean core length for Gleason upgrading on RP (42.7%, n = 76) was 11.61 (±2.5, median 11.40) compared to 13.52 (±3.2, median 13.70), p < 0.001 for perfect biopsy-RP Gleason agreement (57.3%, n = 102). In multivariate analysis, for each unit of core length increment in millimeter, the Gleason upgrading risk decreased 89.9%, p = 0.049 [odds ratio (OR) 0.10, 95% confidence interval (CI) 0.01-0.99]. Biopsy positivity between experienced (35.5%) and in-training performer (30.1%) was not significantly different (p = 0.20), with comparable mean patient age (65.1 vs. 64.1), prostate volume (52.3 vs. 50.7) and median PSA (5.2 vs. 5.1), respectively. Denoting wider variability in terms of core length, in-training performers obtained significantly larger cores for positive biopsies (11.33 ± 3.42 vs. 10.83 ± 3.68), p = 0.043, compared to experienced performer (11.39 ± 3.36 vs. 11.37 ± 3.64), p = 0.30. In multivariate analysis, PSA density (OR 1.14, 95% CI 1.02-1.28) and age (OR 1.04, 95% CI 1.01-1.07) were significantly associated with biopsy positivity, p = 0.021 and p = 0.011, respectively.

conclusionWhile core length on trans-rectal biopsy independently affects Gleason upgrading on RP specimens, performer experience has minor impact on Gleason discordance or biopsy positivity due to a sharp learning curve.