Association Between Tumor Multifocality on Multi-parametric MRI and Detection of Clinically-Significant Prostate Cancer in Lesions with Prostate Imaging Reporting and Data System (PI-RADS) Score 4

Objective: To investigate whether presence of multifocality on multi-parametric magnetic resonance imaging would increase the likelihood of detecting clinically-significant prostate cancer in a PI-RADS 4 lesion.

Methods: We identified patients with at least 1 PI-RADS 4 lesion who underwent multi-parametric magnetic resonance imaging-ultrasound fusion prostate biopsy. Patients were grouped into 1 of 4 cohorts-cohort 1 (a PI-RADS 4 index lesion and an additional PI-RADS 2 or 3 lesion), cohort 2 (single lesion with PI-RADS 4), cohort 3 (2 or more PI-RADS 4 lesions), or cohort 4 (a PI-RADS 4 lesion and an index lesion with PI-RADS 5). We compared the rate of grade group (GG) ≥ 2 pathology on targeted biopsy of PI-RADS 4 lesions between cohorts and evaluated clinical and radiological factors associated with cancer detection.

Results: The overall rate of GG ≥ 2 pathology in the PI-RADS 4 lesions was 35.2%. The rate of GG ≥ 2 pathology in the cohorts 1, 2, 3, and 4 was 21.7%, 36.3%, 49.1%, and 42.7%, respectively (P< .001). On multivariable analysis, age (OR1.06, P < .001), clinical stage T2 (OR1.59, P= .03), prostate-specific antigen density (OR1.43, P < .001), peripheral zone lesion (OR1.62, P = .04), and study cohort (cohort 2 vs 1, OR1.93, P = .006; and cohort 3 vs 1, OR3.28, P < .001) were significantly associated with the risk of GG ≥ 2 in the PI-RADS 4 lesion.

Conclusion: On targeted biopsy of the PI-RADS 4 lesions, the proportion of GG ≥ 2 pathology is approximately 35%. Rate of GG ≥ 2 detection in PI-RADS 4 lesions might differ based on their location, multifocality, and PI-RADS classifications of other lesions identified.