Pelvic lymph-node staging with 18F-DCFPyL PET/CT prior to extended pelvic lymph-node dissection in primary prostate cancer - the SALT trial -

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.

Prospective comparison of 18F-PSMA-1007 PET/CT, whole-body MRI and CT in primary nodal staging of unfavourable intermediate- and high-risk prostate cancer

“…Many prospective studies that have used histopathology as a validation have already demonstrated adequate diagnostic performance of PSMA PET/CT in primary nodal staging [12,13,[17][18][19]. However, only a small number of prospective multimodality comparative studies are available [20][21][22], and none conducted using 18 F-PSMA-1007 tracer.…”

“…To date, only a limited number of studies evaluating 18 Flabelled PSMA tracers in the detection of PCa regional lymph node metastases have been published [11][12][13].…”

Prostate-specific membrane antigen (PSMA)-based imaging in localized and advanced prostate cancer: a narrative review

“…After histopathologic confirmation, the node-based sensitivity and PPV of 18 F-DCFPyL were 31-42% and 78-91%, respectively (21). Comparable node-and patient-based sensitivities of 34.7% and 41.2% were observed in another trial of 18 F-DCFPyL PET/CT in patients with intermediate-to-high-risk PC undergoing RP with PLND (the SALT trial) (22). Finally, 68 Ga-PSMA-11 PET imaging was directly compared to conventional imaging in a large multicenter randomized clinical trial of 302 men with newly diagnosed high-risk PC (ProPSMA).…”

“…68 Ga-PSMA-11 PET/CT significantly outperformed conventional imaging, with diagnostic accuracies of 92% and 65%, sensitivities of 85% and 38%, and specificities of 98% and 91%, respectively (23). Importantly, selection for a higher risk population and lack of a confirmatory pelvic nodal dissection in most cases may have contributed to the higher sensitivity and PPV observed in ProPSMA compared to other studies of PSMA-based imaging in patients with clinically localized PC (20)(21)(22)(23).…”

Nuclear Imaging for Bone Metastases in Prostate Cancer: The Emergence of Modern Techniques Using Novel Radiotracers

“…The treatment plan was adjusted after 18 F-DCFPyL in 17% (n = 27) of the patients. Jansen et al [53] prospectively analyzed 117 patients who underwent imaging prior to robot-assisted radical prostatectomy and extended pelvic lymph node dissection, in order to determine the diagnostic accuracy of 18 F-DCFPyL PET/CT for pelvic lymph node staging in intermediate-(36.8%) and high-risk (63.3%) PCa. Histological lymph node metastases were found in 17/117 (14.5%) patients, of whom seven had a suspicious PET/CT, resulting in a limited sensitivity (41.2%), but high specificity (94.0%).…”