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

Background: A 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. Objective: To 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 participants: Multicentric 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 analysis: PET/CT results were compared with histologic findings and analyzed in terms of sensitivity, specificity, and accuracy. Multivariable regression analyses were performed. Results and limitations: Overall 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. Conclusions: The 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 summary: The 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. The ability of 11C-choline positron emission tomography/computed tomography to predict the site of nodal relapses is impaired by high false-positive rates in the iliac-obturator region and, more alarmingly, high false-negative rates in the common iliac, sacral, and retroperitoneal regions.