Improving the Gleason grading accuracy of transrectal ultrasound-guided biopsy

摘要

Background: Transrectal ultrasound (TRUS)-guided prostate biopsy is the technique of choice for the assessment of clinical suspicion of prostate cancer (PC) based on abnormal digital rectal examination (DRE) and/or elevated or rising levels of prostate-specific antigen (PSA). Purpose: To identify factors involved in TRUS-guided prostate biopsy, which can be modified by radiologists in order to improve Gleason score (GS) accuracy, and to assess the influence of clinical variables. Material and Methods: We carried out a retrospective review of the records of 185 patients with PC treated surgically at our hospital between 2005 and 2008. Biopsy schemes were classified according to the number of cores (<=7, 8-9, 10-11, 12-15) and the needle length (11, 16, 20 mm). Clinical characteristics - age, family history of PC, DRE, PSA levels, and sonographic data - and prostatectomy GS (pGS) were collected. Results: Non-random concordance between biopsy Gleason score (bGS) and pGS was obtained for 36% of patients (P< 0.001). Under- and over-staging were 30% and 4%, respectively. Concordance was correlated with the core number (45% for <=7, 54% for 8-9, 85% for 10-11, and 80% for 12-15; P<0.00l), but not with the needle length. The concordance rate showed a seven-fold increase when 10-11 cores were obtained (95% Cl, 2-18; P<0.001) compared to those cases in which the core number obtained was <=7. Among clinical variables, only PSA correlated with concordance, showing an inverse relationship. Conclusion: The Gleason correlation values were not improved when 12 or more cores were collected. These values reached a plateau beyond that number of samples. Therefore, when determining treatment strategies, physicians must consider the biopsy scheme used since it has proven to be a predictor of the accuracy of the PC grading system.