TPS138 Background: Disease persistence or relapse following curative-intent surgery or radiotherapy of high-risk prostate cancer is not uncommon. This is attributable, in part, to a failure of accurate staging with diagnostic imaging being insensitive for detection of small volume metastatic disease. 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 sensitivity. The hypotheses of this study are that PSMA-PET/CT (a) has improved diagnostic accuracy compared to conventional imaging, (b) should be used as a first-line diagnostic test for staging, (c) the improved diagnostic accuracy will result in significant management impact and (d) provides economic benefits when incorporated into the management algorithm. Methods: This is a 300 patient phase III multi-centre randomized study of patients with untreated high-risk prostate cancer defined by Gleason grade group 3-5, PSA ≥ 20ng/ml or clinical stage ≥ T3. Patients are randomized to Gallium-68-PSMA11 PET/CT or conventional imaging, consisting of computer tomography of the abdomen/pelvis and bone scintigraphy with SPECT/CT. Patients with negative, equivocal or oligometastatic disease 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. Accuracy is defined by a pre-defined “ground truth” scoring system incorporating histopathologic, imaging and clinical follow-up at six months post randomisation. Secondary objectives include comparing management impact, the number of equivocal studies, the incremental value of second-line imaging in patients who cross-over, health economics, 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. 294 of 300 (98%) patients randomised at time of abstract submission. Clinical trial information: 12617000005358.
PD40-11 THE ROLE OF 68GA-PSMA PET-CT IN INITIAL STAGING OF TREATMENT-NAïVE HIGH RISK PROSTATE CANCER.