Pelvic lymph-node staging with 18F-DCFPyL PET/CT prior to extended pelvic lymph-node dissection in primary prostate cancer - the SALT trial -
B.H.E. Jansen, Yves J. L. Bodar, Gerben J.C. Zwezerijnen, Dennie Meijer, J. Patrick van der Voorn, Jakko A. Nieuwenhuijzen, Maurits Wondergem, Ton A. Roeleveld, Ronald Boellaard, Otto S. Hoekstra, R. Jeroen A. van Moorselaar, Daniela E. Oprea‐Lager, André N. Vis
Abstract
Abstract Purpose The detection of lymph-node metastases (N1) with conventional imaging such as magnetic resonance imaging (MRI) and computed tomography (CT) is inadequate for primarily diagnosed prostate cancer (PCa). Prostate-specific membrane antigen (PSMA) PET/CT is successfully introduced for the staging of (biochemically) recurrent PCa. Besides the frequently used 68 gallium-labelled PSMA tracers, 18 fluorine-labelled PSMA tracers are available. This study examined the diagnostic accuracy of 18 F-DCFPyL (PSMA) PET/CT for lymph-node staging in primary PCa. Methods This was a prospective, multicentre cohort study. Patients with primary PCa underwent 18 F-DCFPyL PET/CT prior to robot-assisted radical prostatectomy (RARP) with extended pelvic lymph-node dissection (ePLND). Patients were included between October 2017 and January 2020. A Memorial Sloan Kettering Cancer Centre (MSKCC) nomogram risk probability of ≥ 8% of lymph-node metastases was set to perform ePLND. All images were reviewed by two experienced nuclear physicians, and were compared with post-operative histopathologic results. Results A total of 117 patients was analysed. Lymph-node metastases (N1) were histologically diagnosed in 17/117 patients (14.5%). The sensitivity, specificity, positive predictive value and negative predictive value for the 18 F-DCFPyL PET/CT detection of pelvic lymph-node metastases on a patient level were 41.2% (confidence interval (CI): 19.4–66.5%), 94.0% (CI 86.9–97.5%), 53.8% (CI 26.1–79.6%) and 90.4% (CI 82.6–95.0%), respectively. Conclusion 18 F-DCFPyL PET/CT showed a high specificity (94.4%), yet a limited sensitivity (41.2%) for the detection of pelvic lymph-node metastases in primary PCa. This implies that current PSMA PET/CT imaging cannot replace diagnostic ePLND. Further research is necessary to define the exact place of PSMA PET/CT imaging in the primary staging of PCa.