Prostate zonal impact of 5α‐reductase inhibitors on multiparametric MRI characteristics and detection of prostate cancer

Objectives To assess the impact of 5α‐reductase inhibitors (5‐ARIs) on multiparametric magnetic resonance imaging (mpMRI) features of Prostate Imaging‐Reporting and Data System (PI‐RADS) lesions and their influence on the detection of clinically significant prostate cancer (csPCa), with a focus on differences between prostate zones. Patients and Methods We retrospectively reviewed data from 1108 PI‐RADS version 2 score 3–5 lesions in 718 patients across a multi‐institutional cohort, all of whom underwent magnetic resonance imaging (MRI)‐targeted biopsy. A subset of 66 lesions from patients receiving 5‐ARI therapy was matched to lesions from untreated patients and independently reviewed by an experienced radiologist in a blinded fashion. Apparent diffusion coefficient (ADC) values were quantified for each lesion and for peripheral and transition zones. Results Among the 1108 lesions, 90 (8%) were in patients on 5‐ARI therapy for ≥3 months prior to mpMRI. Multivariable analysis demonstrated that 5‐ARI use was associated with significantly reduced odds of detecting csPCa on targeted biopsy (odds ratio [OR] 0.32, 95% confidence interval [CI] 0.18–0.57). Stratified analysis revealed a pronounced reduction in csPCa detection in peripheral zone lesions (OR 0.20, 95% CI 0.05–0.68), but not in transition zone lesions (OR 0.38, 95% CI 0.11–1.18). Blinded radiological review showed higher mean ADC values in peripheral zone lesions among 5‐ARI users (869 vs 765 mm 2 /s; P = 0.04) and lower lesion conspicuity ( P = 0.027). There were no significant imaging differences in the transition zone. Conclusions Treatment with 5‐ARIs is associated with decreased detection of csPCa on MRI‐targeted biopsy, especially for peripheral zone lesions. These effects may be attributable to increased ADC values and reduced lesion conspicuity, suggesting a potential increase in false‐positive mpMRI findings in patients receiving 5‐ARIs.