Introduction: Adequate localization on multiparametric magnetic resonance imaging (mpMRI) and biopsy sampling of the prostate is important for focal therapy options for prostate cancer (PCa) where oncologic control is tied to accurate spatial identification of PCa. However, PCa tends to be multifocal, limiting potential candidates for treatment. The aim of the present study was to quantify (1) biopsy-confirmed mpMRI detected multifocality of PCa and (2) proportion of patients who may be focal therapy candidates based on comparison of mpMRI-fusion targeted biopsy findings to systematic biopsy.
Methods: Adult men without a prior diagnosis of PCa receiving mpMRI prior to prostate biopsy with targeted and systematic cores in the Prospective Loyola University mpMRI Prostate Biopsy Cohort (2015-2021) were included for evaluation. Patients with PI-RADS 3-5 lesions were classified by a three-level approach of mpMRI lesions (single, multiple unilateral, and contralateral), targeted biopsy findings, and systematic biopsy findings. Patients with single targeted biopsy-confirmed grade group 2 lesions and concordant systematic biopsy findings were defined as focal therapy candidates. Multivariable logistic regression evaluated predictors of mpMRI-undetected contralateral PCa.
Results: Of 897 included patients, 450 (50.2%) had a single, 141 (15.7%) had multiple unilateral, and 306 (34.1%) had contralateral lesions on mpMRI. Of men with single lesions, 38.5% biopsy-naïve vs. 20.6% prior negative biopsy were targeted biopsy-confirmed (p < 0.001). Overall rate of targeted-biopsy confirmed single lesion and multifocal PCa was 257/897 (28.7%; 167/503 (33.2%) biopsy-naïve subset) and 93/897 (10.4%; 80/503 (15.9%) biopsy-naïve subset). Based on systematic biopsy among single targeted-biopsy confirmed patients, 92/257 (35.8%) had contralateral PCa missed by mpMRI with DRE (OR 3.26 (95%CI 1.38-7.72), p=0.007), PSA, and biopsy history identified as significant predictors on multivariable logistic regression. 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 grade group restrictions, 61/897 (6.8%; 30/503 (6.0%) biopsy-naïve subset) remained potential focal therapy 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 grade group 2 mpMRI lesion potentially amenable to focal therapy.
Source of Funding: Efforts to support data extraction and maintenance of The Prospective Loyola University mpMRI Prostate Biopsy Cohort database is supported by funding from Siemens Medical Solutions USA, Inc.
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