Collaborative Review – Prostate CancerCan Clinically Significant Prostate Cancer Be Detected with Multiparametric Magnetic Resonance Imaging? A Systematic Review of the Literature
Introduction
A major concern related to prostate cancer (PCa) screening and early detection is overdiagnosis and overtreatment of indolent disease. Strategies to reduce overdiagnosis are necessary, as are strategies to differentiate indolent from aggressive tumours [1].
The conventional diagnostic pathway in men with elevated serum prostate-specific antigen (PSA) levels and/or abnormal digital rectal examination consists of a random systematic transrectal ultrasound (TRUS)-guided prostate biopsy (PB) [2]. The main disadvantages are that (1) TRUS-guided PB misses a substantial proportion of significant PCa (approx. 20%) because of sampling errors, especially in the anterior part of the prostate gland [3], [4], and (2) a high proportion of men are diagnosed with clinically insignificant disease, which may result in subsequent overtreatment.
Owing to its high soft-tissue contrast, high resolution, and ability to simultaneously image functional parameters, magnetic resonance imaging (MRI) provides the best visualisation of the prostate compared to other imaging methods. Over the past years, MRI use has shifted from staging purposes to detection and tumour localisation. PB based on MRI findings improves PCa detection over systematic TRUS-guided PB [5]. Functional techniques, such as diffusion-weighted MRI (DW-MRI), dynamic contrast-enhanced MRI (DCE-MRI), and/or MR spectroscopy imaging (MRSI) [6], [7], [8], [9], [10], in addition to conventional T2-weighted anatomical sequences (multiparametric MRI, mpMRI), have resulted in accurate PCa localisation [11], [12], [13], [14] and allow image-guided targeted sampling to overcome the limitations of the traditional blind PB.
mpMRI detects both high-grade and larger tumours accurately, which means it may perform particularly well for detection of clinically significant disease [10]. Evidence is being gathered to identify cancers of significant volume. Moreover, these functional techniques may be used to differentiate between low- and intermediate/high-grade PCa [15], [16], [17], [18]. These characteristics make MRI a potential tool for ruling out significant disease. The next step that will be taken is to identify cancers of significant grade (Gleason 4 or 5 component) independent of the volume. DW-MRI is the most promising technique for investigating not only tumour size but also aggressiveness [16].
The aim of the present study was to perform a systematic review of the literature to determine the diagnostic accuracy of mpMRI for the detection of clinically significant PCa.
Section snippets
Search strategy
A literature search using the Medline and Embase databases, Cochrane reviews, and the Cochrane database of clinical trials was performed. The following inclusion criteria were used: humans; male gender; adult; English language and publication date from January 1, 2000 until September 30, 2014. The search terms used were “prostate OR PCa OR PSA OR prostatic OR prostate cancer” AND “MR OR NMR OR NMRI OR MRI OR magnetic resonance OR ADC OR DWI OR DCE OR diffusion weighted OR dynamic contrast OR
Evidence synthesis
The systematic literature search revealed 1729 records. The first step was to screen the titles and abstracts and remove duplicates, which yielded 525 potentially eligible studies that used MRI (Fig. 1). Another 188 studies were excluded because mpMRI was performed after PB, leaving 337 papers for full review. Of these 337 studies, 325 did not meet the inclusion criteria. Twelve studies were included for full analysis (Table 1, Table 2, Table 3, Table 4, Table 5, Table 6) [22], [25], [26], [27]
Conclusions
mpMRI is able to detect significant PCa in biopsy-naïve males and men with prior negative biopsies. The high negative predictive value of mpMRI is important because mpMRI could be used to rule out significant disease. This may result in fewer or no systematic or targeted biopsies in patients with PSA suspicious for prostate cancer.
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