Prostate cancer upgrading with serial prostate MRI scans and repeat biopsy in men on active surveillance: are confirmatory biopsies still necessary?

OBJECTIVES: To investigate whether serial prostate magnetic resonance imaging (MRI) may guide the utility of repeat targeted (TBx) and systematic biopsy (SBx) when monitoring men with low-risk prostate cancer (PCa) at one-year in active surveillance (AS). MATERIALS AND METHODS: We retrospectively included 111 consecutive men with low-risk (ISUP grade 1) PCa, who received protocolled repeat MRI with or without TBx and repeat SBx at one-year AS. TBx was performed in PI-RADS score >/=3 lesions (MRI-positive men). Upgrading defined as ISUP grade >/=2 PCa (I), grade >/=2 with cribriform growth/intraductal carcinoma PCa (II), and grade >/=3 PCa (III) was investigated. Upgrading detected by TBx only (not by SBx) and SBx only (not by TBx) was investigated in MRI-positive and MRI-negative men, and related to radiological progression on MRI (PRECISE score). RESULTS: Overall upgrading (I) was 32% (35/111). Upgrading in MRI-positive and MRI-negative men was 48% (30/63) and 10% (5/48) (p <0.001), respectively. In MRI-positive men, upgrading was in 23% (7/30) by TBx only and in 33% (10/30) by SBx only. Radiological progression (PRECISE score 4-5) in MRI-positive men was observed in 27% (17/63). Upgrading (I) occurred in 41% (7/17) of these MRI-positive men, while this was 50% (23/46) in MRI-positive men without radiological progression (PRECISE score 1-3) (p =0.534). Overall upgrading (II) was 15% (17/111). Upgrading in MRI-positive and MRI-negative men was 22% (14/63) and 6% (3/48) (p =0.021), respectively. In MRI-positive men, upgrading was 21% (3/14) by TBx only and 50% (7/14) by SBx only. Overall upgrading (III) was 5% (5/111). Upgrading in MRI-positive and MRI-negative men was 6% (4/63) and 2% (1/48) (p =0.283), respectively. In MRI-positive men, upgrading was 25% (1/4) by TBx only and 50% (2/4) by SBx only. CONCLUSION: Upgrading is significantly lower in MRI-negative compared to MRI-positive low-risk PCa men at one-year surveillance. In serial MRI-negative men, the added value of repeat SBx at one-year surveillance is limited and should be balanced individually against the harms. In serial MRI-positive men, the added value of repeat SBx is substantial. Based on this cohort, SBx is recommended to be performed in combination with TBx in all MRI-positive men at one-year surveillance, also when there is no radiological progression.