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Authors Nguyen HG, Conn CS, Kye Y, et al.
Review Date May 2018
Citation N Engl J Med. 10;378(19):1767-1777
Men that are suspected to have prostate cancer are generally referred for a standard transrectal ultrasonography-guided prostate biopsy. This standard biopsy method is linked to under-detection of clinically significant cancers, and over-detection of clinically insignificant cancers. The latter can lead to over-treatment of patients who do not benefit from treatment and can sometimes be adversely affected by treatment side-effects.
Recent advances in multiparametric magnetic resonance imaging (MRI) technology has led to the evaluation of this method as an alternative first-step in the diagnostic pathway for prostate cancer. This non-invasive tool is proposed as a powerful approach for determining the presence prostate cancer, if the cancer is clinically significant or insignificant, and if considered significant allow for the targeted biopsy of abnormal lesions based on MRI data. Importantly, it would reduce the number of men undergoing an unnecessary prostate biopsy procedure and facing associated side-effects associated with this intervention.
PRECISION (Prostate Evaluation for Clinically Important Disease: Sampling Using Image Guidance or Not?) is a multicentre, randomised clinical trial that aimed to evaluate multiparametric MRI as a risk-assessment tool to triage men suspected to have prostate cancer, for or not for, subsequent MRI-targeted biopsy.
This prospective clinical trial was conducted across 25 centres in 11 countries, recruiting 500 men (mean age 64 years) suspected of prostate cancer, based on a high prostate-specific antigen (PSA) reading or an abnormal digital rectal examination, and no previous history of a prostate biopsy. Men were randomly assigned at a 1:1 ratio to receive MRI with or without subsequent targeted biopsy (based on MRI result), or standard ultrasonography-guided biopsy. Subjects in the MRI group who were classified as equivocal, likely or highly likely to have prostate cancer were referred for targeted biopsy. Diagnoses of clinically significant prostate cancer (Gleason score sum of 7 or higher) or clinically insignificant cancer (Gleason score sum of 6) were measured as primary and secondary outcomes post-biopsy.
Of the patients assigned to the MRI group, more than one-quarter (28%) had an MRI result that did not indicate prostate cancer; therefore those patients did not receive a biopsy. The remaining 72 per cent of patients had a ‘positive’ MRI result and subsequently underwent a biopsy.
Clinically significant prostate cancer was identified in a higher proportion of patients in the MRI with or without targeted biopsy group (38%; 95/252) compared to the standard biopsy group (26%; 64/248; P<0.01). Clinically insignificant prostate cancer was identified in fewer patients in the of the MRI-targeted biopsy group (9%; 23/252) than the standard biopsy group (22%; 55/248; P<0.001).
MRI with or without targeted biopsy was found to be superior to standard transrectal ultrasonography-guided biopsy in the detection of clinically significant prostate cancer. Adoption of MRI screening prior to the decision on whether or not to undergo a biopsy would improve the identification of men with clinically significant cancer who would benefit from treatment. At the same time this approach would minimise the number of men found to have clinically insignificant cancer who go on to receive unnecessary ‘over-treatment’ of a non-life threatening cancer.
Points to Note
1. Fewer biopsy cores were obtained in the MRI-targeted biopsy group compared to the standard biopsy group (median: 4 vs 12).
2. Given the targeted nature of the MRI-targeted biopsy, a significantly greater proportion of core biopsy samples were positive for cancer in the MRI group (44%) compared to the standard biopsy group (18%).
3. Health-related quality of life scores at 24 hours and 30 days after biopsy treatment were not different between MRI-targeted or standard biopsy groups; however, twice the number of men self-reported complications including blood in urine, blood in semen, and pain at the site of the biopsy 30 days after the intervention when receiving standard compared to MRI-targeted biopsy. The authors suggest this reflects the lower number of core biopsies obtained in the MRI-targeted group.
4. Other well-powered single- and multi-centre studies (including the PROMIS study; Lancet 2017 389(10071):815) and a published meta-analysis study (Eur Urol 2015 68(3): 438), identify results concordant with that of this study, suggesting that an MRI-based diagnostic pathway is advantageous over standard straight-to-biopsy interventions.
5.The strengths of this study are its large size and global reach, indicating that the results are applicable across different regions with differing health systems and approaches. Participant centres were allowed to use different protocols and equipment for MRI, meaning that the results of this study should be largely generalisable.
6.The limitations of this study (noted by the authors) were some inconsistency in the interpretation of MRI results, determined through quality-control checks. This highlights the need for improvements to the standardisation, reproducibility and reporting of results obtained via multiparametric MRIs.