Recently, Haidar et al. conducted a systematic review to investigate the role of MRI targeted approach in the diagnosis of prostate cancer in biopsy naïve men and in men with prior negative biopsies [2]. Their systematic review included articles published up to 2014. The authors concluded that according to current evidence, MRI targeted approach should not be considered the standard of care in biopsy naïve patients. Is this still true today and does the size of the prostate really matters?
We live in an era of evidence based medicine where personalized approach is gaining popularity. In 2015, the results of two randomized clinical trials (level 1 evidence) comparing MRI targeted approach to the 2D TRUS guided biopsy in prostate biopsy-naïve patients were published. In the first, Tontilla et al. demonstrated similar diagnostic accuracy between cognitive mpMRI/TRUS fusion targeted biopsy and 2D TRUS guided biopsy [3]. In the second, the proportion of men with clinically significant prostate cancer was statistically higher in the group of MRI targeted biopsy compared to 2D TRUS guided group [4]. In light of these level 1 evidence studies, it is obvious that we cannot recommend mpMRI and MRI targeted biopsy for all biopsy naïve men at higher risk of prostate cancer. However, a specific subgroup of patients could benefit from such an approach.
First, none of the 130 men with a negative mpMRI, in the already cited randomized study, had any Gleason pattern 4 identified on saturation biopsy [4]. In another study, normal mpMRI was associated with NPV as high as 97.5% for clinically significant disease in men with PSA ≤ 10µg/L and a prostate volume ≤ 33mL. Thus, a subsequent number of patients could be spared biopsy if mpMRI is performed. Second, the proportion of patients harboring an indolent disease is decreased when an MRI targeted approach is offered. Recently, the results of a multicenter controlled non inferiority trial demonstrated that MRI targeted biopsies were inferior to systematic biopsy for overall cancer detection rate [5]. However, as a secondary end point, the detection of clinically significant prostate cancer did not differ between targeted and systematic biopsies. Therefore, if these results are confirmed, MRI targeted approach could decrease detection rate of indolent prostate cancer. Third, mpMRI performed prior to biopsy, would decrease the number of subsequent biopsies in active surveillance protocols in patients diagnosed with a clinically non-significant disease [1]. Fourth, in patients with an enlarged prostate, we demonstrated in our study high detection rate for clinically significant prostate cancer when using the MRI targeted approach compared to standard biopsy [6]. Fifth, patients with anterior or apical lesion on MRI could be better sampled by MRI targeted biopsy [7].
We acknowledge several limitations to offer mpMRI for every patient at higher risk for prostate cancer. The majority of published data have come from excellence center with extensive experience with mpMRI. These results may not be reproducible in less experienced centers. The availability of mpMRI is also another limitation. Despite the standardization of the characterization of the index lesion in the PIRADS score, inter-observer variability is not uncommon in clinical practice. Furthermore, the long term impact of such an approach is not well determined. However, while awaiting the results of the PICTURE study and the PROMIS trial, that will help to better understand the clinical utility of mpMRI in the diagnosis of clinically significant prostate cancer, we think that mpMRI should be performed only in biopsy naïve patient with enlarged prostate (> 50 mL in our study). Our hypothesis is that mpMRI plays a pivotal role in selecting these patients before biopsy and it decreases as well the sampling error that is more prevalent in enlarged prostates.
Written by: Fouad Aoun, Elie El Rassy, Maroun Moukarzel
Corresponding author: Fouad Aoun, MD, MSc, Jules Bordet Institute, 1 Rue Héger Bordet, 1000 Brussels, Belgium - Saint Joseph University, Department of Urology, Hotel Dieu de France, Beirut, Lebanon.
References
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- Haider MA, Yao X, Loblaw A, Finelli A. Multiparametric Magnetic Resonance Imaging in the Diagnosis of Prostate Cancer: A Systematic Review. Clin Oncol (R Coll Radiol). 2016
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- Delongchamps NB, Portalez D, Bruguière E, Rouvière O, Malavaud B, Mozer P, Fiard G, Cornud F. Are Magnetic Resonance Imaging-Transrectal Ultrasound Guided Targeted Biopsies Noninferior to Transrectal Ultrasound Guided Systematic Biopsies for the Detection of Prostate Cancer in Patients with a Single Suspicious Focus on Multiparametric Prostate Magnetic Resonance Imaging? Results of a Multicenter Controlled Trial. J Urol. 2016
- Peltier A, Aoun F, Albisinni S, Marcelis Q, Ledinh D, Paesmans M, Lemort M, van Velthoven R. Results of a comparative analysis of magnetic resonance imaging-targeted versus three-dimensional transrectal ultrasound prostate biopsies: Size does matter. Scand J Urol. 2016 Jun;50(3):144-8. doi: 10.3109/21681805.2015.1118408. Epub 2016 Jan 12.See comment in PubMed Commons below
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