A prospective randomised multi-centre study of the impact of Ga-68 PSMA-PET/CT imaging for staging high risk prostate cancer prior to curative-intent surgery or radiotherapy (proPSMA study): clinical trial protocol.

Abstract

Accurate staging of patients with prostate cancer is important for therapeutic decision making. Relapse following surgery or radiotherapy of curative intent is not uncommon and, in part, represents a failure of staging with current diagnostic imaging techniques to detect disease spread. Prostate-specific-membrane-antigen (PSMA) positron emission tomography / computed tomography (PET/CT) is a new whole body scanning technique that enables visualisation of prostate cancer with high contrast. The hypotheses of this study are that (a) PSMA-PET/CT has improved diagnostic performance compared to conventional imaging, (b) PSMA-PET/CT should be used as a first-line diagnostic test for staging, (c) the improved diagnostic performance of PSMA-PET/CT will result in significant management impact and (d) there are economic benefits if PSMA-PET/CT is incorporated into the management algorithm. This is a prospective, multi-centre study in which patients with untreated high-risk prostate cancer will be randomised to Gallium-68-PSMA11-PET/CT or conventional imaging, consisting of computer tomography of the abdomen/pelvis and bone scintigraphy with SPECT/CT. Inclusion criteria are newly diagnosed prostate cancer patients with select high-risk prostate cancer defined as International Society of Urological Pathology (ISUP) grade group ≥ 3 (primary Gleason grade 4, or any Gleason grade 5), PSA ≥ 20ng/mL or clinical stage ≥ T3. Patients with negative, equivocal or oligometastatic disease on first line-imaging will cross-over to receive the other imaging arm. The primary objective is to compare the accuracy of PSMA-PET/CT to conventional imaging for detecting nodal or distant metastatic disease. Histopathologic, imaging and clinical follow-up at six months will define the primary endpoint according to a pre-defined scoring system. Secondary objectives include comparing management impact, the number of equivocal studies, the incremental value of second-line imaging in patients who cross-over, the cost of each imaging strategy, radiation exposure, inter-observer agreement and safety of PSMA-PET/CT. Longer term follow-up will also assess the prognostic value of a negative PSMA-PET/CT. This trial will provide data to establish whether PSMA-PET/CT should replace conventional imaging in the primary staging of select high-risk localised prostate cancer patients, or whether it should be used to provide incremental diagnostic information in selected cases. The proPSMA study is registered in the Australian and New Zealand Clinical Trial Registry (ANZCTR Trial No. 12617000005358). This clinical trial is funded by a grant from the The Movember Foundation through Prostate Cancer Foundation of Australia's Research Program. This article is protected by copyright. All rights reserved.