PSMA-PET identifies PCWG3 target populations with superior accuracy and reproducibility when compared to conventional imaging: a multicenter retrospective study.

Background: Prostate-specific membrane antigen (PSMA)-ligand positron-emission-tomography (PSMA-PET) is potentially useful for screening of castration resistant prostate cancer (CRPC) clinical trial target populations. Aim: We investigated the impact of PSMA-PET on Prostate Cancer Clinical Trials Working Group 3 (PCWG3) clinical subtype classification when compared to conventional imaging (CI). Methods: Multicenter retrospective study enrolling patients with (a) PSMA-PET for CRPC, (b) PSA values ≥1 ng/mL and (c) CI, i.e. CT plus bone scan or whole-body MRI. Clinical PCWG3 subtype was determined for PET vs. CI by three blinded readers. Results: 67 patients were included and PSMA-PET led to up-staging in 15% (10/67) of patients, of these 6/10 (60%) had CI non-metastatic CRPC. PSMA-PET resulted in down-staging in 15% (10/67) of patients. Agreement for PET vs. CI PCWG3 clinical subtype was 0.81 vs. 0.51, 0.74 vs. 0.47, 0.95 vs. 0.72, or 0.59 vs. 0.66 for local, nodal, bone, or visceral disease, respectively. Conclusion: PSMA-PET demonstrated major concordance with CI for per-patient PCWG3 clinical subtype and should be implemented in future CRPC clinical trial screening procedures.