18F-PSMA-11 Versus 68Ga-PSMA-11 Positron Emission Tomography/Computed Tomography for Staging and Biochemical Recurrence of Prostate Cancer: A Prospective Double-blind Randomised Cross-over Trial.

Fluorine-18 (18F)-labelled prostate-specific membrane antigen (PSMA) offers several advantages over gallium-68 (68Ga) in terms of costs, yield, transport/distribution, and image resolution.

This trial investigates the new radiotracer 18F-PSMA-11 via a prospective, intraindividual crossover design. The trial was powered for noninferiority of 18F-PSMA-11 over 68Ga-PSMA-11 positron emission tomography (PET)/computed tomography (CT) in terms of the number of positive PET scans. Secondary endpoints were as follows: (1) superiority of 18F-PSMA-11 over 68Ga-PSMA-11 with respect to the number of positive PET scans, the total number of suspicious prostate cancer lesions, and the miPSMA expression score of corresponding lesions; (2) correlation of the PET/CT images with available follow-up data for 18F-PSMA-11 and 68Ga-PSMA-11; and (3) assessment of the interobserver variability.

Prostate cancer patients (primary or biochemical recurrence) were randomised in a double-blind crossover design whereby each patient received both 18F-PSMA-11 and 68Ga-PSMA-11 PET/CT.

All scans were reviewed and scored by three independent experienced nuclear physicians following the proposed guideline for the interpretation of PSMA-ligand PET/CT, as described by Eiber et al. RESULTS AND LIMITATIONS: In total, 82 patients were included for scan analyses. The primary endpoint was met: per patient, the proportions of positive scans rated by the three readers were 67%/67%, 65%/65%, and 73%/70% for 18F-PSMA-11/68Ga-PSMA-11 PET/CT. The miPSMA expression score was higher for 18F-PSMA-11 than for 68Ga-PSMA-11 for the reference reader. Follow-up data showed identical estimated sensitivity for both the 18F-PSMA-11 and the 68Ga-PSMA-11 scan (0.92, 0.83, and 0.92 for the three readers). A fair to good agreement among readers (at patient level) was obtained, which was demonstrated by a Light's kappa value of 0.59 for both tracers.

The tracer 18F-PSMA-11 is noninferior to68Ga-PSMA-11. Superiority of 18F-PSMA-11 was limited to the miPSMA expression score, given by the reference reader. Inter-rater agreement was fair to good, and equal for both radiotracers.

In this study, we compared two radiotracers: 18F-PSMA-11 and 68Ga-PSMA-11. We proved that 18F-PSMA-11 is not inferior to 68Ga-PSMA-11 for detecting prostate cancer and thus can be used as an alternative. Possible superiority of this tracer should be further investigated in specific subpopulations.

European urology. 2022 Jun 08 [Epub ahead of print]

Kathia De Man, Nick Van Laeken, Vanessa Schelfhout, Wolfgang P Fendler, Bieke Lambert, Ken Kersemans, Sarah Piron, Nicolaas Lumen, Karel Decaestecker, Valérie Fonteyne, Louke Delrue, Filip De Vos, Piet Ost

Department of Medical Imaging, Nuclear Medicine, Ghent University Hospital, Ghent, Belgium. Electronic address: ., Department of Medical Imaging, Nuclear Medicine, Ghent University Hospital, Ghent, Belgium., Department of Nuclear Medicine, University of Duisburg-Essen and German Cancer Consortium (DKTK)-University Hospital Essen, Essen, Germany., Department of Nuclear Medicine, AZ Maria Middelares, Ghent, Belgium; Department of Nuclear Medicine, AZ Jan Palfijn, Ghent, Belgium; Department of Diagnostic Sciences, Ghent University, Ghent, Belgium., Laboratory of Radiopharmacy, Ghent University, Ghent, Belgium., Department of Urology, Ghent University Hospital, Ghent, Belgium., Department of Radiation-Oncology, Ghent University Hospital, Ghent, Belgium., Department of Medical Imaging, Radiology, Ghent University Hospital, Ghent, Belgium., Department of Diagnostic Sciences, Ghent University, Ghent, Belgium; Department of Radiation-Oncology, Iridium Network, Wilrijk, Belgium.

email news signup