Using Prostate Imaging-Reporting and Data System (PI-RADS) Scores to Select an Optimal Prostate Biopsy Method: A Secondary Analysis of the Trio Study

Abstract

Background: While magnetic resonance imaging (MRI)-targeted biopsy (TBx) results in better prostate cancer (PCa) detection relative to systematic biopsy (SBx), the combination of both methods increases clinically significant PCa detection relative to either Bx method alone. However, combined Bx subjects patients to higher number of Bx cores and greater detection of clinically insignificant PCa.

Objective: To determine if prebiopsy prostate MRI can identify men who could forgo combined Bx without a substantial risk of missing clinically significant PCa (csPC).

Design, setting, and participants: Men with MRI-visible prostate lesions underwent combined TBx plus SBx.

Outcome measurements and statistical analysis: The primary outcomes were detection rates for grade group (GG) ≥2 and GG ≥3 PCa by TBx and SBx, stratified by Prostate Imaging-Reporting and Data System (PI-RADS) score.

Results and limitations: Among PI-RADS 5 cases, nearly all csPCs were detected by TBx, as adding SBx resulted in detection of only 2.5% more GG ≥2 cancers. Among PI-RADS 3-4 cases, however, SBx addition resulted in detection of substantially more csPCs than TBx alone (8% vs 7.5%). Conversely, TBx added little to detection of csPC among men with PI-RADS 2 lesions (2%) relative to SBx (7.8%).

Conclusions: While combined Bx increases the detection of csPC among men with MRI-visible prostate lesions, this benefit was largely restricted to PI-RADS 3-4 lesions. Using a strategy of TBx only for PI-RADS 5 and combined Bx only for PI-RADS 3-4 would avoid excess biopsies for men with PI-RADS 5 lesions while resulting in a low risk of missing csPC (1%).

Patient summary: Our study investigated an optimized strategy to diagnose aggressive prostate cancer in men with an abnormal prostate MRI (magnetic resonance imaging) scan while minimizing the risk of excess biopsies. We used a scoring system for MRI scan images called PI-RADS. The results show that MRI-targeted biopsies alone could be used for men with a PI-RADS score of 5, while men with a PI-RADS score of 3 or 4 would benefit from a combination of MRI-targeted biopsy and systematic biopsy. This trial is registered at ClinicalTrials.gov as NCT00102544.

Keywords: Combined biopsy; Fusion biopsy; Prostate Imaging-Reporting and Data System; Prostate cancer; Prostate cancer diagnosis; Prostate magnetic resonance imaging.

Fig. 1 –

Flow chart of patient enrollments and study exclusions, which resulted in the final study population of 723 men with magnetic resonance imaging (MRI)-visible prostate lesions. PI-RADS = Prostate Imaging-Reporting and Data System.

Fig. 2 –

Cancer detection rates by PI-RADS score and biopsy method. The total cancer detection rate (stratified by grade group) for systematic, MRI-targeted, and combined biopsy among men with PI-RADS 2–5 lesions. Detection rates for total cancer and clinically significant cancer were highest among the men with the highest PI-RDAS scores. MRI-targeted biopsy resulted in higher detection of clinically significant cancer (grade group ≥2) than systematic biopsy for men with PI-RADS 4 (p < 0.001) or PI-RADS 5 (p = 0.003) lesions. The data shown in the graph are mirrored in the table underneath, which also shows detection rates for grade group ≥2, grade group ≥3, and any cancer detection. Results for the statistical analysis are shown in Supplementary Figure 2. MRI = magnetic resonance imaging; PI-RADS = Prostate Imaging-Reporting and Data System.

Fig. 3 –

Added value of systematic and targeted biopsy for detection of clinically significant cancer by biopsy method. Proportion of patients for whom additional (A) grade group ≥2 or and (B) grade group ≥3 prostate cancer was detected by MRI-targeted biopsy or systematic biopsy. Additional cancer detection is defined as grade group ≥2 (or grade group ≥3) that is only identified by one biopsy method but detected as a lower grade or no cancer by the other biopsy method. The results demonstrate that for patients with highly abnormal prostate MRI (high PI-RADS score) the added detection of clinically significant cancer with MRI-targeted biopsy greatly exceeds that with systematic prostate biopsy. However, among patients with less significant prostate MRI abnormalities (PI-RADS 2–3), systematic biopsy detects more clinically significant cancers than MRI-targeted biopsy alone. MRI = magnetic resonance imaging; PI-RADS = Prostate Imaging-Reporting and Data System.