BERKELEY, CA (UroToday.com) - The ideal biopsy strategy for identifying prostate cancer would successfully identify men with clinically significant cancer whilst overlooking men with clinically insignificant cancer, and in doing so, require only a small number of biopsies thus reducing biopsy burden. MRI-targeted biopsy is a promising biopsy technique which has been thought to possess these advantages.[1]
MRI prior to biopsy can be used to identify suspicious lesions in the prostate, which can be targeted during a subsequent biopsy. We compared the detection rate of clinically significant and clinically insignificant cancer by transperineal MRI-targeted biopsy (MRI-TB) with transperineal template-guided prostate biopsy (TPB). The population was comprised of 182 men who presented to our group between February 2010 and March 2012 and were offered biopsy based on clinical suspicion of prostate cancer due to a raised PSA or abnormal digital rectal examination. All men underwent pre-biopsy MRI followed by MRI-TB and TPB. We used a primary threshold definition for clinically significant cancer of at least one biopsy core with maximum cancer core length ≥ 4mm and/or Gleason Grade ≥ 3+4 (UCL definition 2).
Clinically significant cancer detection with MRI-TB and TPB was 57% (103/182) and 62% (113/182), respectively (p=0.174). Clinically insignificant cancer detection with MRI-TB and TPB was 9.3% (17/182) and 17.0% (31/182), respectively (p=0.024). These results demonstrate that MRI-TB detects a similar amount of clinically significant cancer and less insignificant cancer than TPB. MRI-TB achieves this with fewer biopsies. Thus this provides evidence supporting the use of MRI-TB as a biopsy strategy.
Limitations of the study include the retrospective data collection. There is also no universally accepted method of MRI conduct or universally accepted histological definition of clinical significance based on MRI-targeted biopsy. However we used standards for MRI conduct derived from a European consensus meeting[2] and definitions for clinically significance that have been previously derived.[3]
In addition, we used visual registration as the method of registering the suspicious lesion identified on MRI to the transrectal ultrasound image seen during the biopsy procedure. It is acknowledged that other methods of registration exist, such as software registration, and that other methods of guidance exist, such as in-bore MRI-guided biopsy.
Future work would involve assessing the clinical effectiveness of MRI-targeted biopsy in prospective trials to corroborate these findings. Prior to considering the use of such a biopsy technique, a comparison to standard of care, transrectal ultrasound guided biopsy should be carried out, taking into consideration the cost effectiveness and resources required for both biopsy procedures.
References:
- Moore, C. M., Roberson, N. L., N., A. et al.: Image guided prostate biopsy using MRI derived targets- a systematic review. European Urol (in press), 2012
- Dickinson, L., Ahmed, H. U., Allen, C. et al.: Magnetic resonance imaging for the detection, localisation, and characterisation of prostate cancer: recommendations from a European consensus meeting. Eur Urol, 59: 477, 2011
- Ahmed, H. U., Hu, Y., Carter, T. et al.: Characterizing clinically significant prostate cancer using template prostate mapping biopsy. J Urol, 186: 458, 2011
Written by:
Veeru Kasivisvanathan, MBBS, BSc, MRCS as part of Beyond the Abstract on UroToday.com. This initiative offers a method of publishing for the professional urology community. Authors are given an opportunity to expand on the circumstances, limitations etc... of their research by referencing the published abstract.
NIHR Academic Clinical Fellow
Royal College of Surgeons CEU & London School of Surgery
