Detection of clinically significant prostate cancer after negative fusion and systematic biopsy.

Abstract

288 Background: MRI/Ultrasound fusion biopsy of the prostate has enhanced the detection of clinically significant prostate cancer (csPCa). Detection of csPCa is greatest when fusion and systematic biopsies are combined. However, the finding of a negative fusion and negative systematic biopsy in patients with suspicious lesion on imaging raises the question of either falsely positive imaging or a false negative biopsy. Methods: We retrospectively reviewed our database of patients undergoing MRI/transrectal US-guided fusion biopsy. All images were graded according to the Prostate Imaging Reporting and Data System version (PIRADS) 2.0. Patients underwent targeted biopsy followed by systematic 12-core double sextant biopsy within the same session. csPCa was defined as Grade Group (GG) ≥2 PCa. Patients with no prostate cancer (PCa) found on biopsies were followed. MRI studies with PIRADS v2 score ≤ 2 were considered to have no MRI evidence of PCa. Results: A total of 400 patients had at least one PIRADS ≥3 lesion and underwent fusion/systematic biopsy. Of these, 113 (28.3%) patients had no evidence of PCa on either fusion or systematic biopsy. Median follow-up was 32.5 months. 44 (39%) patients underwent repeat MRI and of these, 24 (54%) had no evidence of PCa on repeat MRI. PIRADS lesion disappearance was associated with lower PSA Density (PSAd) (0.12 vs 0.20; P = 0.0319) and decreased progression to repeat biopsy (8.33% vs 95%; P < 0.0001). Patients who had a repeat biopsy had a greater PSAd ( 0.21 vs 0.12; P = 0.0054). Of 113 patients with negative initial biopsy, 23 (20.4 %) underwent repeat biopsy: 16 (14.2 %) had PCa and 11 (9.7%) had csPCa. Thus, 48% of patients who underwent repeat biopsy had csPCa. Among patients with a PCa on repeat biopsy, cancer was sampled by MRI targeted cores in 80% of patients. Conclusions: Despite a negative initial fusion/systematic biopsy, at least 10% of patients were subsequently diagnosed with clinically significant PCa. The combination of elevated PSAd and the persistence of a suspicious lesion on repeat MRI appears selective for previously missed PCa. However, after negative fusion biopsy, repeat MRI yields a high rate of PIRADS lesion disappearance in patients with low PSAd.