Refining the risk-stratification of transrectal biopsy-detected prostate cancer by elastic fusion registration transperineal biopsies.

PURPOSE: To evaluate image-guided Transperineal Elastic-Registration biopsy (TPER-B) in the risk-stratification of low-intermediate risk prostate cancer detected by Transrectal-ultrasound biopsy (TRUS-B) when estimates of cancer grade and volume discorded with multiparametric Magnetic Resonance Imaging (MRI). METHODS: All patients referred for active surveillance or organ-conservative management were collegially reviewed for consistency between TRUS-B results and MRI. Image-guided TPER-B of the index target (IT) defined as the largest Prostate Imaging-Reporting Data System-v2 ≥ 3 abnormality was organized for discordant cases. Pathology reported Gleason grade, maximum cancer core length (MCCL) and total CCL (TCCL). RESULTS: Of 237 prostate cancer patients (1-4/2018), 30 were required TPER-B for risk-stratification. Eight cores were obtained [Median and IQR: 8 (6-9)] including six (IQR: 4-6) in the IT. TPER-B of the IT yielded longer MCCL [Mean and (95%CI): 6.9 (5.0-8.8) vs. 2.6 mm (1.9-3.3), p < 0.0001] and TCCL [19.7 (11.6-27.8) vs. 3.6 mm (2.6-4.5), p = 0.0002] than TRUS-B of the gland. On TPER-B cores, longer MCCL [Mean and (95%CI): 8.7 mm (6.7-10.7) vs. 4.1 mm (0.6-7.6), p = 0.002] were measured in Gleason score-7 cancers. TPER-B cores upgraded 13/30 (43.3%) patients. 14/30 (46.7%) met University College London-definition 1 and 18/30 (60.0%) definition 2, which correlate with clinically significant cancers > 0.5 mL and > 0.2 mL, respectively. 7/16 (43.8%) patients under active surveillance were re-allocated toward prostatectomy (n = 5) or radiation therapy (n = 2). In 14 patients not yet assigned, TPER-B risk-stratification spurred the selection (13/14, 92.9%) of treatments with curative intent. CONCLUSION: Image-guided TPER-B of the index target provided more cancer material for pathology. Subsequent re-evaluation of cancer volume and grade switched a majority of patients towards higher-risk groups and treatments with curative intent.