ASCO GU Cancers Symposium 2018 Live Coverage

CUA 2017: Correlation of Transperineal Prostate Biopsy-Detected Cancer with Magnetic Resonance Imaging-Predicted Lesion in Patients with Previous Negative Transrectal Ultrasound-Guided Prostate Biopsies

Toronto, Ontario (UroToday.com) Introduction of multiparametric MRI (mpMRI) has drastically changed the landscape of prostate cancer (PCa) diagnostics. However, as with any diagnostic tool, learning to better select patients for appropriate use, especially in a cost-effective manner, is critically important. While originally touted to be an excellent discriminator between clinically significant prostate cancer and indolent disease, more recent results have been sobering; false negatives still persist in the range of 10-20%. In contrast, template mapping biopsies done via a transperineal approach (TPB) reported have a yield of approximately 38% in men with prior negative TRUS biopsies. 

In this study, the authors assess their institutional experience of men who underwent an mpMRI and TPM following an initially negative TRUS prostate biopsy. In a 3-year period, there were 70 patients who met the study criteria; median age was 66 years (43–81) years and median prostate-specific antigen (PSA) 9.6 ug/L (0.7–33.9).  

PCa was detected in the TPM in 43 (56%) patients, and 34 (82%) patients had Gleason score ≥7 lesions. PIRADS 4/5 lesion was seen in 34 (47%), and 26 (76%) of these had PCa concordance with biopsy results. Overall, location concordance with MRI findings was seen in 32 (46%) patients, but discordance was due to benign histology in 28 (38%). Patients with proven PCa had 74% concordance with MRI.

At the end of the day, this implies that 40% of PCa diagnoses were discordant with mpMRI findings. An important conclusion that the authors draw is that a targeted biopsy in the absence of a concurrent systematic 12-core biopsy is not appropriate in this population. 

However, this is a small population of selected patients. A trial of patients, similar to the PROMIS study,1 which was done in biopsy naïve patients, would be better able to answer this question. While I agree with the authors that a systematic biopsy is still warranted on repeat biopsy to evaluate for cancers not detectable on MRI, further evidence is required.

Presented By: Ewan Semple, Core Surgical Trainee, Department of Urology, Ninewells Hospital, Dundee, United Kingdom 

Co-Authors: Hassen Ahmeidat, Ghulam Nabi, Ghulam M Nandwani
Institutions: Ninewells Hospital, NHS Tayside, Dundee, United Kingdom

Written By: Thenappan Chandrasekar, MD (Clinical Fellow, University of Toronto  Twitter: @tchandra_uromd at the  72nd Canadian Urological Association Annual Meeting - June 24 - 27, 2017 - Toronto, Ontario, Canada

References:
1. Ahmed HU, El-Shater Bosaily A, Brown LC, Gabe R, Kaplan R, Parmar MK, Collaco-Moraes Y, Ward K, Hindley RG, Freeman A, Kirkham AP7, Oldroyd R, Parker C, Emberton M; PROMIS study group. Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study. Lancet. 2017 Feb 25;389(10071):815-822. doi: 10.1016/S0140-6736(16)32401-1. Epub 2017 Jan 20.