Clinical utility of MR/ultrasound fusion-guided biopsy in patients with lower suspicion lesions on active surveillance for low-risk prostate cancer

Background: The utility of Multiparametric magnetic resonance imaging (mpMRI) guided prostate biopsy among patients with prostate cancer (CaP) managed with active surveillance (AS) with low-suspicion lesions remains unsettled.

Methods: We performed a retrospective analysis of 415 men with low-risk CaP managed with active surveillance. We selected men with mpMRI visible index lesions scored as 2 or 3 according to Prostate Imaging Reporting and Data System (PI-RADS) version 2. The primary outcome was detection of clinically significant prostate cancer (csCaP) was defined as Gleason grade group ≥ 2. We assessed the diagnostic accuracy of biopsy approaches using area under the receiver operator characteristic (ROC) curve and evaluated factors associated with csCaP in these patients using multivariate logistic regression.

Results: CsCaP was identified in 22 of 125 patients (17.6%) with PI-RADS 2 or 3 index lesions during surveillance prostate biopsies. These included 10 (45.5%) diagnosed by systematic biopsy alone, 9 (40.9%) by targeted alone, and 3 (13.6%) by both approaches. On multivariable analysis, the only significant variable predicting the detection of csCaP in men with low-risk imaging mpMRI characteristics was higher PSAD (OR per 0.1 unit=2.26, 95% CI 1.25-4.06, P = 0.007. A PSAD cutoff of 0.1, 0.12 and 0.15 resulted in a negative predictive value (NPV) of 90.9%, 87.1% and 86.2%, respectively. When stratified by PI-RADS score, a PSAD cutoff of 0.1, 0.12 and 0.15 resulted in NPV of 96.2%, 90.6% and 89.7% and 86.2%, 84.2% and 83.3% for detection of csCaP in PI-RADS 2 and 3 lesions, respectively. In patients with PIRDAS 2 lesions, using a PSAD of 0.1 would potentially allow 51% of patients to avoid biopsy with only a 3.8% chance of missing csCaP.

Conclusion: In men with clinical low-risk prostate cancer on active surveillance with PI-RADS 2 and 3 lesions, there is an almost 18% risk of upgrade to csCaP. Integration of PSAD may be a useful adjunctive tool in identifying patients at highest risk for upgrade despite favorable imaging findings. In men with PIRADS 2 lesions with PSAD ≤0.12 biopsy can be avoided. For men with PIRADS 2 lesions with PSAD ≤0.15 informed decision making regarding the AS intensity should include that these patients have a low risk (>10%) of developing csCaP. In men with PIRADS 3 lesions with PSAD >0.1, shared decision making should include discussion of a >10% miss rate of csCaP.