Login to Access Video or Poster Abstract: MP43-07
Sources of Funding: none

Introduction

The role of magnetic resonance imaging (MRI)/fusion biopsy for prostate cancer patients on active surveillance (AS) remains unclear.

Methods

We compared MRI/fusion guided targeted biopsy (TB) to standard ultrasound-guided systematic biopsy (SB) for detection of clinically significant cancer in AS patients undergoing confirmatory biopsy. The primary outcome was upgrading defined as detection of Gleason sum ≥ 3 + 4 =7 disease.

Results

Of 356 AS patients at our institution, 195 (58%) underwent prostate MRI after the initial diagnostic biopsy. Of these, 138 (71%) had MRI-detectable lesions. After implementation of TB in May 2014, 42 AS patients underwent confirmatory MRI/fusion TB: n=9 (21.4%), n=19 (45.2%), n=7 (16.7%), and n=7 (16.7%) with PI-RADS 2, 3, 4, and 5 lesions, respectively. Compared to SB patients undergoing confirmatory biopsy (n=106), TB patients had higher PSA (5.3 ng/mL versus 3.5 ng/mL, p<0.001) and modestly higher PSA density (0.14 versus 0.09, p=0.01). There were no significant differences in age (0.29), BMI (p=0.21), family history (p=0.1.0), comorbid diseases (p=0.26-1.0), number of prior biopsies (p=0.167), or time since cancer diagnosis (p=0.58). Gleason sum ≥ 3 + 4 = 7 was diagnosed in 30 (29%) SB patients and 16 (38%) TB patients (p=0.33). Stratification by PI-RADS revealed Gleason ≥ 3 + 4 = 7 diagnosis in 0 (0%), 4 (21%), 6 (86%) and 6 (86%) of PI-RADS 2, 3, 4, and 5 lesions, respectively (p<0.001). Compared to SB, TB of PI-RADS ≥ 4 lesions detected 58% more Gleason ≥ 3 + 4 = 7 cancers (86% versus 28%, p<0.0001) and was associated with increased odd of upgrading in multivariable regression (p=0.012). The positive predictive value (PPV) of PI-RADS ≥ 4 lesions for Gleason ≥ 3 + 4 = 7 disease was 86%. Sensitivity analyses of patients with only 1 biopsy prior to confirmatory biopsy produced similar results.

Conclusions

A majority of patients on AS have MRI-detectable lesions. Compared to SB, selective TB of PI-RADS 4 and 5 lesions improves the detection of clinically significant cancers in those undergoing confirmatory biopsy.

Funding

none