The CADMUS Trial: A Paired Cohort, Blinded Study Comparing Multiparametric Ultrasound Targeted Biopsies with Multiparametric MRI Targeted Biopsies in the Detection of Clinically Significant Prostate Cancer

5008 Background: Multiparametric MRI (mpMRI) of the prostate followed by targeted biopsy is recommended in men at risk of prostate cancer. Dissemination of this pathway may be limited by cost, variable scan and reporting quality, and contraindicated in the presence of metallic implants and claustrophobia. Multi-parametric ultrasound (mpUSS) is a point of care test with low cost that combines b-mode, colour Doppler, elastography and contrast enhancement. CADMUS compared the diagnostic performance of mpUSS to mpMRI. Methods: CADMUS recruited 370 patients from seven sites to a prospective, multicentre, paired-cohort trial (ISRCTN 38541912). Ethics committee approval was obtained. Patients underwent both mpUSS and mpMRI independently, each with a positive test defined as a Likert score of >3. Those with either a positive mpUSS or mpMRI, or both, were advised to undergo targeted biopsies. Reporting of each scan was carried out blind to the other and prior to biopsy; patients advised for biopsy were blinded to which test was positive. The order of mpUSS and mpMRI targeting was randomised. Primary outcomes were proportion of positive tests and detection of clinically significant cancer (csPCa) defined as Gleason >4+3 of any length and/or maximum cancer core length of >6mm of any grade [PROMIS definition1]. Results: 306 completed both mpUSS and mpMRI. Agreement in lesion detection between mpUSS and mpMRI was 73.2% (kappa 0.06, p = 0.14). 257 with positive results on mpUSS, mpMRI or both had targeted biopsies. Agreement on detection of csPCa was 91.1% (expected 59.8%, kappa 0.78, p < 0.01). Overall, mpUSS detected 4.3% fewer csPCa than mpMRI (95% CI = [-8.3%, -1.5%]; p = 0.042 [Bonferroni correction]). mpUSS detected 7.2% (6/83) csPCa missed by mpMRI; mpMRI detected 20.5% (17/83) csPCa that mpUSS missed. At a less stringent definition of significant cancer, Gleason grade >3+4 of any length (definition 3), agreement was 89.1% (expected 55.6%, kappa 0.75, p < 0.01) mpUSS detected 5.4% fewer definition 3 cancers than mpMRI overall. mpUSS detected 7% (7/99) definition 3 cancers that mpMRI missed; mpMRI detected 21% (21/99) definition 3 cancers that mpUSS missed. Conclusions: The CADMUS trial shows mpUSS has a diagnostic performance approaching that of mpMRI and significant cancer detection is improved by the use of both scans over mpMRI alone. Clinical trial information: 38541912. [Table: see text]