Improving the Gleason grading accuracy of transrectal ultrasound-guided biopsy

Abstract

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 < 0.001), but not with the needle length. The concordance rate showed a seven-fold increase when 10–11 cores were obtained (95% CI, 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.