Assessment of the Minimal Targeted Biopsy Core Number per MRI Lesion for Improving Prostate Cancer Grading Prediction

Abstract

Background: To study the impact of MRI characteristics and of targeted biopsy (TB) core number on the final grade group (GG) prediction. Materials and Methods: The cohort was 478 consecutive patients who underwent radical prostatectomy (RP) after positive mpMRI (multiparametric magnetic resonance imaging) followed by fusion TB. Endpoints were the upgrading and concordance rates between TB and RP specimens. Results: Upgrading rate after TB was 40.6%. Patients with upgrading had lower PIRADS (Prostate Imaging-Reporting and Data System) scores (p < 0.001), smaller lesion size (p = 0.017), fewer TB cores (p < 0.001), and lower TB density (p = 0.015) compared with cases with grade concordance. There was a significant continuous improvement in upgrading rate when TB core number per lesion increased from 56.3% to 25.6% when <2 or ≥5 TB cores were taken, respectively (p = 0.002). The minimal TB number per lesion to reduce upgrading risk to approximately 30%was 4 in PIRADS 3, and 3 in PIRADS 4–5 cases. Conclusions: Grade group prediction by TB is significantly improved by higher PIRADS score, larger lesion size, and increased TB per lesion. At least four TB cores should be taken in PIRADS 3 score lesions, whereas three cores seem enough in PIRADS 4–5 cases to improve GG prediction and limit upgrading risk.

Combined Systematic and MRI-US Fusion Prostate Biopsy Has the Highest Grading Accuracy When Compared to Final Pathology

“…Using this approach, Calio et al showed a decrease in the upgrading rate from 18% in patients without saturation biopsy to 7% when saturation biopsy of the index lesion was performed ( p = 0.021) [ 20 ]. Furthermore, Ploussard et al showed that obtaining a minimum of 4 cores in the case of 3 PIRADS lesions and a minimum of 3 cores in the case of 4–5 PIRADS lesions can lead to a 30% reduction in the upgrading rate [ 21 ]. However, in current clinical practice, the urologist performing the systematic biopsy is not blinded to the MRI, and frequently, the systematic targeting becomes cognitive-guided.…”

Managing Discordant Findings Between Multiparametric Magnetic Resonance Imaging and Transrectal Magnetic Resonance Imaging–directed Prostate Biopsy—The Key Role of Magnetic Resonance Imaging–directed Transperineal Biopsy

“…Software-assisted elastic-fusion registration was preferred to the template method as it required fewer cores and was feasible under local anesthesia [13]. In this setting, we obtained a median number of four cores from the IT, which was recently demonstrated in a cohort of 478 PI-RADS 3 targets to be sufficient to control under grading [22].…”

Transperineal systematic biopsies in addition to targeted biopsies are important in the detection of clinically significant prostate cancer

“…Furthermore, there was a heterogenous number of targeted cores taken (2–10), potentially further contributing to missed csPC by TB. Studies have suggested the need for higher number of cores (greater than 2) for higher‐grade cancers 25,26 . Whilst this was the case, however, only 15 patients had two cores taken for TB and five patients had less than 12 cores taken for SB, given the small lesion size.…”