Correlation between MRI, biopsy results and radical prostatectomy histological analysis, application to focal therapy

Prostate cancer localization is essential before performing focal therapy. We analyzed the concordance between MRIs, systematic and targeted biopsies, and whole prostate gland removals with the aim of half-gland treatment.

Between 2016 and 2022, we analyzed 132 patients who benefited from positive MRIs (i.e. PI-RADS≥3), biopsies (ISUP 2-3) and radical prostatectomies (RP). MRIs were performed in any imaging office, without double reading. Biopsies were taken after MRI/US fusion by prostate cancer specialist urologists. The hemi-gland of significant prostate cancer localization was collected on MRIs (PI-RADS), biopsies (ISUP) and prostatectomies. Concordance analyses and predictive values were calculated between MRIs and biopsies, MRIs and RPs, biopsies and RPs, and in the concordant MRI/biopsy and RP population. ISUP 1 was considered as negative.

Concordance rates vary from 74.24% to 85.05%; Kappa's ratio from 0.42 to 0.65. Neither MRIs nor biopsies detect a significant prostate locus in 24% of cases. PPVs and NPVs for MRIs/biopsies and prostatectomies are 99% and 51.5%, respectively. Grading prediction is accurate in 85% of cases.

The concordance rate is moderate with NPVs synonymous with the risk of undertreatment. The absence of MRI target (but with significant carcinoma after RPs) is a key part of this risk but not always corrected with systematic standard biopsies. Targeted biopsies confirm the MRI foci.

Due to significant cancer in negative MRI areas, the selection method before focal therapy, i.e. half-gland treatment, may be improved and underlines the importance of systematic biopsies.