📃 Paper Title: Diagnostic accuracy of multi-parametric MRI and TRUS biopsy in prostate cancer (PROMIS): a paired validating confirmatory study
🧍 Author: Hashim Ahmed
🕒 Year: 2017
📚 Journal: The Lancet
🌎 Country: United Kingdom
ㅤContext to the study:
What are the advantages of using MRI pre-biopsy (+/- with subsequent MRI-targeted biopsy) versus simply performing a TRUS systematic biopsy alone?
ㅤ✅ Take-home message of study:
This is the first study to present blinded data on the diagnostic accuracy of mpMRI and TRUS biopsy against an accurate reference standard in biopsy-naïve suspected to have prostate cancer. It represents level 1b evidence for assessment of diagnostic accuracy.
mpMRI used as a triage test may lead to approximately one quarter of men being able to omit biopsy safely, also leading to an overall 5% reduction in detection of clinically-insignificant cancers. If biopsy was directed by mpMRI findings, this may lead to a 17% increase in detection of clinically-significant cancer.
ㅤ Prospective, multicentre paired-cohort diagnostic study.
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Study participants:
740 men were enrolled between 2012-2015, of whom 576 underwent both index tests (1.5 T mpMRI and TRUS biopsy) and the reference test (transperineal template prostate mapping biopsy).
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Key study outcomes:
Primary outcome
71% men had cancer of any description detected on the reference test (template biopsy). 'Clinically-significant' cancer, defined as ISUP grade group ≥3 and/or maximum cancer core length (MCCL) ≥6mm, was detected by the reference test in 40%
Sensitivity of mpMRI for detection of clinically-significant cancer was 93%, with NPV 89%. Specificity was 41%, and PPV 51%
27% had a negative mpMRI, of whom 17 men (11%) had clinically-significant cancer on the reference test. All of these men had ISUP grade group ≤2 but MCCL of 6-12mm
mpMRI had significantly greater sensitivity than TRUS biopsy (93% vs 48%) and significantly greater NPV (89% vs 74%). TRUS, however, had better specificity (41% vs 96%) and PPV (51% vs 90%)
Using mpMRI pre-biopsy to triage men may allow 27% of men to avoid a biopsy, and would produce a 5% reduction in diagnosis of clinically-insignificant findings
If subsequent biopsy was directed by mpMRI findings, up to 17% more clinically-significant cancer might be detected compared to standard TRUS biopsy
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Study Limitations:
Prostates >100mL were excluded as the 5mm brachytherapy grid used for template biopsy would not be large enough for sampling of the whole gland
Template biopsy was performed first, followed by TRUS biopsy. This could have made TRUS biopsy less accurate due to swelling, distortion, and tissue disruption
No specific MRI-targeted biopsies were performed
Two experts readers reported each scan, and therefore this may not be wholly generalisable to less experienced readers and centres
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