Detection of Clinically-Significant Prostate Cancer on Systematic Biopsy in Patients with a PI-RADS 3-5 Lesion on MRI: Results from a Large Institutional Series.

OBJECTIVES: To evaluate the use of PSA density (PSAD) and MRI findings to identify patients that can safely forgo full or partial systematic biopsy while maintaining detection of Grade Group (GG)>2 prostate cancer. METHODS: From a prospectively maintained database, we performed a retrospective analysis of patients with a positive MRI (PI-RADS ≥3) undergoing systematic and MRI-targeted prostate biopsy. The primary outcome was GG>2 detection on systematic and/or targeted biopsy. After stratification by PI-RADS score and PSAD, we evaluated the risk of failing to detect GG≥2 cancer if full or contralateral systematic biopsies were omitted. RESULTS: Among 1506 patients who met criteria for inclusion, 648 (43%) had GG≥2 cancer on combined biopsy. Rates of GG≥2 cancer increased with higher PI-RADS score (PI-RADS 3:19%, 4:48%, 5:66%) and PSAD (<0.1: 25%, 0.1 to <0.15: 40%, 0.15 to <0.2: 43%, ≥0.2: 62%). Overall, omission of systematic biopsy would have resulted in missing 25% of GG≥2 cancers (11% of the population). Stratification by PI-RADS and PSAD did not reveal any subgroups in which omitting systematic biopsy would have missed cancer in <5% of patients. In patients with a solitary PI-RADS 3-5 lesion, omitting contralateral systematic biopsies would have missed GG≥2 cancer in only 2.6% of patients. CONCLUSION: In a large academic series, use of PSAD and PI-RADS score did not identify patients with PI-RADS ≥3 mpMRI that could safely avoid systematic biopsy altogether. Acknowledging that the generalizability of these data could vary by setting, our findings suggest that omitting contralateral systematic biopsies could reduce overdiagnosis of GG1 disease while preserving detection of the vast majority of GG≥2 cancers.