Is 11C-choline Positron Emission Tomography/Computed Tomography Accurate to Detect Nodal Relapses of Prostate Cancer After Biochemical Recurrence? A Multicentric Study Based on Pathologic Confirmation from Salvage Lymphadenectomy

Abstract

BackgroundA 11C-choline positron emission tomography/computed tomography (PET/CT) scan is used for restaging prostate cancer (PCa) patients with biochemical recurrence (BCR). Only a few reports have focused on the correlation between PET/CT and nodal relapse location at pathologic examination. ObjectiveTo assess the accuracy of PET/CT in predicting the site of nodal relapses in patients undergoing pelvic and/or retroperitoneal salvage lymph node dissection (sLND). Design, setting, and participantsMulticentric retrospective study including 106 patients with BCR of PCa after radical treatment; all patients but six had a PET/CT showing at least one nodal recurrence and received sLND. Outcome measurements and statistical analysisPET/CT results were compared with histologic findings and analyzed in terms of sensitivity, specificity, and accuracy. Multivariable regression analyses were performed. Results and limitationsOverall sensitivity, specificity, negative and positive predictive value, and accuracy of PET/CT for disease location were 61.6%, 79.3%, 66.3%, 75.7%, and 70.2%, respectively. Sensitivity was 75.5% in the lower pelvis with 69.8% specificity. The retroperitoneal region had high specificity (94.7%) but a relatively low sensitivity (58.3%). The sLNDs did not find any positive nodes in 16 patients (15%). According to regression analyses, discriminative accuracy of PET/CT was 70.4% and improved with an increased number of dissected nodes and prostate-specific antigen doubling time <12 mo. Limitations include retrospective design and lack of a standardized sLND template followed for all patients. ConclusionsThe ability of PET/CT to detect nodal relapses is limited by a high false-positive rate, particularly in the iliac-obturator region and, more alarmingly, a high false-negative rate in the common iliac, sacral, and retroperitoneal regions. An extended template including pelvic and retroperitoneal regions should be adopted when sLND is planned for curative intent. Patient summaryThe 11C-choline positron emission tomography/computed tomography scan is a commonly used tool to restage prostate cancer patients with biochemical recurrence, showing an overall per patient accuracy >80%; however, its ability to detect the site of nodal relapses remains suboptimal.