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EAU 2017

EAU 2017: Special session of the Prostate Cancer Prevention Group - Risk factors and biomarkers for screening and triage: Imaging-based biomarkers: mpMRI

London, England (UroToday.com) Dr. Albers discussed in this presentation the question whether multiparametric MRI (mpMRI) can act as a screening tool in the pre-biopsy stage. To answer this question, technical details regarding MRI should be well understood. The biomarker component of the mpMRI is manifested in its ability to measure cell density through the diffusion values. Special software must be used to operate this component and a personal level of experience is needed as well. Radiologists must be familiar with the classification of the mpMRI. PIRADS 1 was first published 5 years ago and PIRADS 2 was just published last year.

According to PIRADS protocol, the radiologist must test a minimum of 39 sections of the prostate. PIRADS 2 is not approved for monitoring in active surveillance, but only approved for detecting clinical significant cancer. A meta-analysis by Woo et al. in European urology 2007 showed that PIRADS 2 has higher sensitivity than PIRADS 1.In practicality, this means that PIRADS 2 does not detect as many cancers as PIRADS 1 detected. This causes the number of patients with a negative mpMRI to be significantly larger than the number of patients diagnosed with a negative mpMRI in PIRADS 1.

A recently published study from Dr. Pinto’s group deals with inter-observer variability in PIRADS 2. The study took 5 radiologists including 2 experienced ones, looking at the prostate MRI of 35 patients and comparing it to the radical prostatectomy specimens. It was demonstrated that the inter-observer agreement was high in PIRADS 4 and above lesions. However, 80% of the MRIs demonstrate PIRADS 3 lesion, where inter-observer variability is high.

Assessing the evidence available to date regarding mpMRI in prostate cancer demonstrates that 30% and 10% of cancer and clinically significant cancer are missed by the mpMRI, respectively.
Only 2 studies exist regarding the role of mpMRI in screening. The first study showed the number of men with biopsies was reduced if they had a mpMRI. Additionally, the detection rate of significant cancers is the same between those undergoing mpMRI and those that not. The second study demonstrated that mpMRI did better than PSA.

Finally Dr. Albers gave some important recommendations:
- Do not use mpMRI in the screening setting, unless in a clinical trial
- mpMRI has to be evaluated and validated on a standardized level
- mpMRI guided biopsies have to be quality controlled
- Don’t lose track on patients with PIRADS 1+2 lesions, because they may harbor undetected significant cancer in 10% of cases.

Concluding the presentation Dr. Albers stated that mpMRI guided screening is not yet ready for prime time.

Presented by: Dr. Peter Albers, Düsseldorf (DE)

Written by: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto

Twitter: @GoldbergHanan

at the #EAU17 -March 24-28, 2017- London, England