Mapping prostate cancer lesions pre/post unsuccessful salvage lymph node dissection using repeat PSMA-PET.

Introduction: The aim of this study was to analyze patterns of persistent versus recurrent or new PET lesions in a selected patient cohort with PSA persistence following salvage lymph node dissection (SLND) and pre/post procedure prostate-specific membrane antigen ligand positron emission tomography (PSMA-PET). Material and Methods: 16 patients were included in this multicenter study. Inclusion criteria were: a) PSMA-PET performed for biochemical recurrence before SLND (pre-SLND PET) and b) repeat PSMA-PET performed for persistently elevated PSA level (≥0.1 ng/mL) ≥6 weeks after SLND (post-SLND PET). Image analysis was performed by three independent nuclear medicine physicians applying the molecular imaging TNM system PROMISE. Lesions were confirmed by histopathology, presence on correlative CT/MRI/bone scan or PSA response after focal therapy. Results: post-SLND PET identified PCa-lesions in 88% (14/16) of patients with PSA persistence after SLND. Median PSA was 1.2 ng/mL (IQR, 0.6-2.8 ng/mL). Disease was confined to the pelvis in 56% of patients (9/16) and most of these men had common iliac (6/16, 38%) and internal iliac lymph node metastases (6/16, 38%). Extrapelvic disease was detected in 31% of patients (5/16). In pre- and post-SLND PET comparison, 10/16 had at least one lesion already detected at baseline (63% PET persistence); 4/16 had new lesions only (25% PET recurrence); 2 had no disease on post-SLND PET. All validated regions (11 regions in 9 patients) were true positive. 9/14 (64%) patients underwent repeat local therapies after SLND (7/14 radiotherapy, 2/14 surgery). Conclusion: SLND of pelvic nodal metastases was often not complete according to PSMA-PET. About two thirds of patients had PET positive nodal disease after SLND already seen on pre-SLND PSMA-PET. Notably, about one quarter of patients had new lesions, not detected by pre-surgical PSMA-PET.

Journal of nuclear medicine : official publication, Society of Nuclear Medicine. 2019 Dec 05 [Epub ahead of print]

Andrea Farolfi, Harun Ilhan, Andrei Gafita, Jeremie Calais, Francesco Barbato, Manuel Weber, Ali Afshar-Oromieh, Fabian Spohn, Axel Wetter, Christoph Rischpler, Boris Hadaschik, Davide Pianori, Stefano Fanti, Uwe Haberkorn, Matthias Eiber, Ken Herrmann, Wolfgang Peter Fendler

Nuclear Medicine Unit, University of Bologna, S. Orsola Hospital, Italy., Department of Nuclear Medicine, University Hospital, Ludwig-Maximilians-Universitaet (LMU), Germany., Department of Nuclear Medicine, Klinikum rechts der Isar, Technical University Munich (TUM), Germany., Ahmanson Translational Theranostics Division, Department of Molecular and Medical Pharmacology, University of California Los Angeles (UCLA), United States., Department of Nuclear Medicine, University Hospital Essen, Germany., Department of Nuclear Medicine, Heidelberg University Hospital, Germany., Department of Radiology, University Hospital Essen, Germany., Department of Urology, University Hospital Essen, Germany., Department of Biomedical and Neuromotor Sciences, University of Bologna, Italy.