Login to Access Video or Poster Abstract: MP38-13
Sources of Funding: Joseph and Diane Steinberg Charitable Trust

Introduction

The use of pre-biopsy MRI for risk stratification of men with no previous history of prostate biopsy remains controversial due to concerns of missed high grade cancers among men with low suspicion MRI. We evaluated the relationship of pre-biopsy MRI and MRI-ultrasound fusion-targeted prostate biopsy (MRF-TB) outcomes among men with no previous history of prostate biopsy.

Methods

Between 6/2012 and 9/2016, 1584 consecutive men presenting to our institution for prostate biopsy underwent pre-biopsy MRI followed by MRF-TB and systematic biopsy (SB), and were prospectively enrolled in an IRB-approved database. We evaluated the outcomes of 800/1584 men who had no previous biopsy. 109 men were excluded due to outside MRI, 1.5T MRI, or hip implants. 35 men were excluded as they did not undergo concomitant SB with MRF-TB. Men with no MRI lesion (MRI score of 1) underwent only SB.

Results

Among 656/800 men who met inclusion criteria (mean age 63±11 years; mean PSA 6.1±3.4 ng/mL), prostate cancer (PCa) was detected in 380 (58%) cases. Cancer detection rates (CDR) for SB and MRF-TB were 54% and 43%, respectively (p < 0.01). MRF-TB detected significantly less Gleason (GS) 6 PCa compared to SB [86/203 (42%) vs 176/203 (87%), p < 0.01] and more GS 3+4 cancers than SB [109/140 (78%) vs 87/140 (62%), p = 0.02]. There was no significant difference in detection of dominant GS pattern 4 PCa (Table 1)._x000D_ _x000D_ When CDR is stratified by MRI score (Table 2), detection of GS 3+4 and GS ≥4+3 in men with an MRI score of 1 or 2 is less than 5%. Deferral of prostate biopsy in 229 men with an MRI score of 1 or 2 would have missed 3% (7) of GS ≥4+3, 5% (11) of GS 3+4, and 28% (63) of GS 6 PCa, of which 75% (47/63) would have been clinically insignificant by Epstein criteria. _x000D_

Conclusions

In men presenting for primary prostate biopsy, MRF-TB detects more GS 3+4 PCa than SB and reduces over-detection of GS 6 by 49%. Deferral of primary prostate biopsy in men with MRI scores of 1 or 2 would miss very few clinically significant PCa while avoiding over-detection of clinically insignificant disease in 21% of these men.

Funding

Joseph and Diane Steinberg Charitable Trust