Risk-stratification based on magnetic resonance imaging and prostate-specific antigen density may reduce unnecessary follow-up biopsy procedures in men on active surveillance for low-risk prostate cancer.

Objectives: To assess the value of risk-stratification based on magnetic resonance imaging (MRI) and prostate-specific antigen density (PSA-D) in reducing unnecessary biopsies without missing Gleason pattern 4 prostate cancer in men on active surveillance (AS).

Patients And Methods: In all, 210 men on AS with Gleason score 3 + 3 prostate cancer received a first MRI and if indicated [Prostate Imaging Reporting and Data System (PI-RADS) score ≥3] targeted biopsy (TBx) using MRI-transrectal ultrasonography (TRUS) fusion. The MRI was performed 3 months after diagnosis (group A: n = 97), at confirmatory biopsy (group B: n = 39) or at surveillance biopsy after one or more repeat TRUS-guided systematic biopsies (TRUS-Bx) (group C: n = 74). The primary outcome was upgrading to Gleason score ≥3 + 4 prostate cancer based on MRI ± TBx in groups A, B and C. Biopsy outcomes were stratified for the overall PI-RADS score and PSA-D to identify a subgroup of men in whom a biopsy could have been avoided as no Gleason score upgrading was detected.

Results: In all, 134/210 (64%) men had a positive MRI and 51/210 (24%) men had Gleason score upgrading based on MRI-TBx. The percentage of Gleason score upgrading based on MRI-TBx was 23% (22/97), 23% (9/39) and 27% (20/74) in respectively groups A, B and C. Additional Gleason score upgrading detected by TRUS-Bx occurred in 8% (3/39) of men in group B and 6% (1/17) of men who received TRUS-Bx in group C. No Gleason score upgrading was detected by MRI-TBx in men with a PI-RADS score of 3 and a PSA-D of <0.15 ng/mL (n = 15), nor by TRUS-Bx in men with a PI-RADS score of 1-3 and a PSA-D of <0.15 ng/mL (n = 15).

Conclusion: At least one out of five men on AS with Gleason score 3 + 3 prostate cancer at diagnostic TRUS-Bx show Gleason score upgrading based on first MRI ± TBx at baseline, confirmatory or surveillance biopsy. Men with a PI-RADS score of 1-3 and PSA-D of <0.15 ng/mL did not show Gleason score upgrading at MRI ± TBx or TRUS-Bx at each time point of surveillance. Thus risk-stratification based on PI-RADS and PSA-D may reduce unnecessary follow-up biopsy procedures in men on AS.