Multifocality of Prostate Cancer and Candidacy for Focal Therapy Based on Magnetic Resonance Imaging

Objectives: To determine the prevalence of multiparametric magnetic resonance imaging (mpMRI)-detected and targeted biopsy-confirmed multifocal and unifocal prostate cancer (PCa) among patients with Prostate Imaging Reporting and Data System (PI-RADS) ≥3 lesions. Focal therapy (FT) options for PCa are tied to accurate spatial identification on mpMRI. Methods: Men without prior diagnosis of PCa receiving mpMRI, targeted and systematic prostate biopsy in the Prospective Loyola Urology mpMRI (PLUM) Prostate Biopsy Cohort from 2015-2021 were included. Patients with PI-RADS ≥3 lesions were classified by mpMRI lesion location, targeted biopsy, and systematic biopsy. Patients with single biopsy-confirmed grade group (GG) 2 lesions and concordant systematic biopsy were defined as FT candidates. Multivariable logistic regression evaluated predictors of mpMRI-undetected contralateral PCa. Results: Of 897 patients, 450 (50.2%) had a single, 141 (15.7%) had multiple unilateral, and 306 (34.1%) had bilateral mpMRI lesions. 28.7% had a single targeted biopsy-confirmed lesion while 10.4% were multifocal. Among single targeted biopsy-confirmed patients, 92/257 (35.8%) had contralateral PCa missed by mpMRI with DRE, PSA, and biopsy history identified as independent predictors. Systematic biopsy findings dropped the rate of single confirmed lesions from 28.7% to 18.4% and multifocal PCa increased from 10.4% to 20.6%. After GG restrictions, 61/897 (6.8%) remained potential FT candidates. Conclusions: Among men with clinical suspicion of prostate cancer receiving mpMRI, 28.7% had a single targeted biopsy-confirmed lesion and 10.4% had multifocality on mpMRI, but many mpMRI-undetected contralateral PCa were identified. Only 6.0% of biopsy-naïve men remained with a single GG2 mpMRI lesion potentially amenable to FT.