Localising occult prostate cancer metastasis with advanced imaging techniques (LOCATE trial): a prospective cohort, observational diagnostic accuracy trial investigating whole–body magnetic resonance imaging in radio-recurrent prostate cancer

Abstract

BackgroundAccurate whole-body staging following biochemical relapse in prostate cancer is vital in determining the optimum disease management. Current imaging guidelines recommend various imaging platforms such as computed tomography (CT), Technetium 99 m (99mTc) bone scan and 18F-choline and recently 68Ga-PSMA positron emission tomography (PET) for the evaluation of the extent of disease. Such approach requires multiple hospital attendances and can be time and resource intensive. Recently, whole-body magnetic resonance imaging (WB-MRI) has been used in a single visit scanning session for several malignancies, including prostate cancer, with promising results, providing similar accuracy compared to the combined conventional imaging techniques. The LOCATE trial aims to investigate the application of WB-MRI for re-staging of patients with biochemical relapse (BCR) following external beam radiotherapy and brachytherapy in patients with prostate cancer.Methods/designThe LOCATE trial is a prospective cohort, multi-centre, non-randomised, diagnostic accuracy study comparing WB-MRI and conventional imaging. Eligible patients will undergo WB-MRI in addition to conventional imaging investigations at the time of BCR and will be asked to attend a second WB-MRI exam, 12-months following the initial scan. WB-MRI results will be compared to an enhanced reference standard comprising all the initial, follow-up imaging and non-imaging investigations. The diagnostic performance (sensitivity and specificity analysis) of WB-MRI for re-staging of BCR will be investigated against the enhanced reference standard on a per-patient basis. An economic analysis of WB-MRI compared to conventional imaging pathways will be performed to inform the cost-effectiveness of the WB-MRI imaging pathway. Additionally, an exploratory sub-study will be performed on blood samples and exosome-derived human epidermal growth factor receptor (HER) dimer measurements will be taken to investigate its significance in this cohort.DiscussionThe LOCATE trial will compare WB-MRI versus the conventional imaging pathway including its cost-effectiveness, therefore informing the most accurate and efficient imaging pathway.Trial registrationLOCATE trial was registered on ClinicalTrial.gov on 18th of October 2016 with registration reference number NCT02935816.

Whole-Body MRI vs. PET/CT for the Detection of Bone Metastases in Patients With Prostate Cancer: A Systematic Review and Meta-Analysis

“…In patients with PCa in whom distant metastases are suspected, whole-body imaging (WBI) (head, neck, torso, and the proximal part of the limbs) can be used to guide the treatments (8,12). Among the available modalities, 18 F-fluoride (NaF) positron emission tomography/computed tomography (PET/CT), 18 F-fluorocholine (FCH) PET/CT, and whole-body magnetic resonance imaging (WBMRI) have been proposed for PCa metastasis detection (9,10,38). WBMRI enables the detection of lymph node metastases and distant metastases in one test (11).…”

Prostate Cancer Diagnostic Algorithm as a “Road Map” from the First Stratification of the Patient to the Final Treatment Decision

“…Wb-MRI with DWI is an effective method for overall staging in PCa, as it can detect metastases in normal-sized lymph nodes and early intramedullary bone metastases before the appearance of cortical destruction or reactive processes [ 30 ]. The LOCATE trial designed to compare the detection of prostate cancer using conventional imaging methods with wb-MRI will certainly yield promising results [ 31 ]. Due to the fact that a whole-body MRI is not a standard imaging method in our hospital, this alternative is not applicable in our case.…”

The future of PSMA PET and WB MRI as next-generation imaging tools in prostate cancer

“…In a study comparing WB-MRI and 68 Ga-PSMA PET-CT following radical prostatectomy, 68 Ga-PSMA PET-CT detected 56 of 56 lesions (100%) in 20 of 28 patients with biochemical recurrence (71.4%), whereas WB-MRI detected 13 lesions (23.2%) in 11 of 28 patients (39.3%) 25 . Results of the LOCATE 26 trial evaluating the diagnostic accuracy of WB-MRI in BCR following radiotherapy are imminent…”