Prostate Imaging Using MRI +/- Contrast Enhancement (PRIME)

A Study Comparing Bi-parametric MRI to Multi-parametric MRI in the Diagnosis of Clinically Significant Prostate Cancer

This prospective clinical trial (PRostate Imaging using Mri +/- contrast Enhancement (PRIME)) aims to assess whether biparametric MRI (bpMRI) is non-inferior to multiparametric mpMRI (mpMRI) in the detection of clinically significant prostate cancer. This means that we are comparing MRI scans that requires injection of IV contrast (the current standard practice) versus MRI scans that can be performed without IV contrast in the detection of prostate cancer.

The PRECISION study (NCT02380027) has established that multiparametric MRI +/- targeted biopsy of suspicious areas identified on MRI is superior to standard 12 core TRUS biopsy in the detection of clinically significant prostate cancer (Gleason > 3+ 4) (38% vs 26%), in reducing the detection of clinically insignificant prostate cancer (Gleason 3 + 3) (9% vs 22%) and in maximising the proportion of cores positive for prostate cancer (44% vs 19%). Multiparametric MRI (mpMRI) typically uses T2-weighted (T2W), diffusion-weighted (DWI) and dynamic contrast enhanced (DCE) sequences. As a mpMRI is a precious resource, due to capacity and resource limitations, one of the major challenges across institutions is delivering a health service with pre-biopsy MRI before a biopsy in all men with suspected prostate cancer. However, biparametric MRI (bpMRI), that is, a combination of T2W and DWI, which does not use the DCE sequences, has demonstrated similar detection rates of prostate cancer as mpMRI in some studies and there is a debate about the necessity of the DCE sequence. The potential advantages of avoiding the DCE sequence include avoiding the cost associated with it, shorter scan time, avoiding the need for medical practitioner attendance, and avoiding putative basal ganglia accumulation and the possibility of adverse neurological effect. Thus, a bpMRI approach may be more feasible and have health-economic benefits over a mpMRI approach and may thus increase the accessibility of this resource to men who need it. PRIME is a multi-centre study. Men referred with clinical suspicion of prostate cancer based on raised prostate specific antigen (PSA) or abnormal digital rectal examination (DRE) who have had no prior biopsy undergo mpMRI. The DCE sequence is blinded from the radiologist who reports the bpMRI first. After reporting the bpMRI, the DCE sequence is made available to the radiologist who reports the mpMRI. The MRIs and lesions are scored on 1-5 scales of suspicion for the likelihood that clinically significant cancer is present: - Very low (clinically significant cancer is highly unlikely to be present) - Low (clinically significant cancer is unlikely to be present) - Intermediate (the presence of clinically significant cancer is equivocal) - High (clinically significant cancer is likely to be present) - Very high (clinically significant cancer is highly likely to be present) Men with non-suspicious MRI on bpMRI and mpMRI and low clinical risk of prostate cancer will be counselled by their clinical teams as per routine clinical care. In routine clinical practice these men typically do not undergo prostate biopsy. Suspicious areas scoring 3, 4 or 5 on either bpMRI or mpMRI will undergo targeted and systematic biopsy using the information from the mpMRI to influence biopsy conduct. Suspicious areas will be labelled by their MRI score, with their location according to sector diagrams. The proportion of patients with clinically significant prostate cancer will be ascertained and compared between bpMRI and mpMRI. Treatment eligibility decisions without the DCE information will be made and once the clinicians are unblinded to the DCE sequence the impact that this information makes on the treatment decision will be evaluated.

Within-person controlled, paired cohort, diagnostic evaluation study. Participants undergo two index tests and a reference test.

Radiologist assessing MRI for suspicion of prostate cancer is blinded to the contrast sequence when reporting the biparametric MRI. After this report, they are unblinded to the contrast sequence and report the multiparametric MRI. All biopsies conducted as a result of MRI findings will be labelled as bpMRI and mpMRI, and diagnostic accuracy will be assessed against histology findings.

MRI with T2-weighted, diffusion weighted and dynamic contrast enhanced sequences followed by prostate biopsy if indicated on MRI and clinical findings

MRI with T2-weighted and diffusion weighted sequences followed by prostate biopsy if indicated on MRI and clinical findings

Score of suspicion on MRI (1-5) - lowest score = 1 = highly unlikely to be significant cancer. Highest score = 5 = highly likely to be significant cancer. For MRI to be non-suspicious it needs to be scored 1 or 2 on both Likert and PIRADSv2.1 systems. For MRI to be suspicious it can to be scored 3, 4 or 5 on either Likert or PIRADSv2.1 systems.

At the coordinating centre, in a multi-disciplinary team meeting, treatment eligibility decisions without the DCE information will be made and once the clinicians are unblinded to the DCE sequence the impact that this information makes on the treatment decision will be evaluated.

When treatment options discussed in multidisciplinary meeting, at an expected average of 30 days post intervention

Test performance characteristics for bpMRI & mpMRI when using the Likert scoring system in comparison to the PIRADS scoring system

Proportion of men with cancer missed by bpMRI and mpMRI-targeted biopsies and detected by systematic biopsy

A within-trial analysis will be conducted to calculate the total cost for bpMRI and mpMRI and mean cost per patient if a strategy of bpMRI or mpMRI were adopted. The cost per diagnosis of clinically significant cancer will be calculated for bpMRI and mpMRI. An incremental cost effectiveness ratio may be calculated by deriving the additional cost per case of clinically significant cancer diagnosed. The cost of avoiding each additional case of clinically insignificant cancer diagnosed may also be calculated. Consideration will be given to extending this analysis using economic modelling to allow a lifetime perspective to be taken and the estimation of quality adjusted life years (QALYs). Costs of procedures will be estimated by multiplying standard unit costs by key resource using data captured within the trial. If possible, standard unit costs (e.g. NHS Reference costs) will be supplemented by unit cost data (and uncertainty around these costs) from the participating trial sites.

Inclusion Criteria: Men at least 18 years of age referred with clinical suspicion of prostate cancer Serum PSA ≤ 20ng/ml Fit to undergo all procedures listed in protocol Able to provide written informed consent Exclusion Criteria: Prior prostate biopsy Prior treatment for prostate cancer Prior prostate MRI on a previous encounter Contraindication to MRI Contraindication to prostate biopsy Unfit to undergo any procedures listed in protocol

Anonymised data will be available at request for bona fide researchers with important research questions subject to approval by the study steering committee.

A study steering committee will review all requests for access to the data and will make decisions on whether or not to grant access to bona fide researchers based on the importance of the research question being asked, ensuring analysis is non overlapping with existing analyses and planned analyses.

https://www.ucl.ac.uk/surgery/research/department-targeted-intervention/urology/prime-trial-information