Presentation Authors: Shawn Dason, Nathan C. Wong*, Andreas Meier, Timothy F. Donahue, Lorenzo Mannelli, Pier Luigi Di Paolo, Lucas W. Dean, Victor A. McPherson, Jonathan E. Rosenberg, Dean F. Bajorin, Guido Dalbagni, H. Alberto Vargas, Bernard H. Bochner, New York, NY
Introduction: The role of preoperative 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) in detecting lymph node metastases at radical cystectomy (RC) is unclear. Herein, we characterized the diagnostic properties of PET/CT for nodal metastases in patients with muscle-invasive urothelial carcinoma (MIUC) undergoing RC.
Methods: Dedicated genitourinary radiologist re-reviewed preoperative 18F-FDG PET/CT scans that were performed on patients with MIUC prior to RC between August 2012 and February 2017. PET/CT was routinely performed prior to RC at our institution during this study period. Findings on PET were considered positive if uptake was above the background blood pool uptake and not attributable to a physiologic or otherwise benign process. All patients underwent templated pelvic lymph node dissection with packeted node submission. This study included a mixed population of clinically relevant patient groups that were assessed as separate cohorts; patients were stratified by clinical node involvement (â‰¥1cm short-axis on CT) and preoperative chemotherapy status. We assessed the diagnostic properties of PET/CT using sensitivity, specificity, positive predictive value, and negative predictive value.
Results: A total of 208 preoperative PET/CT scans (78 pre-chemotherapy, 61 post-chemotherapy, and 69 without chemotherapy) were performed on our cohort of 182 patients. The median time from PET/CT to surgery in those who did not receive chemotherapy was 28 days (IQR 15, 38). The rate of pathologic node positive (pN+) disease was 21.8% in clinically node negative (cN0) patients and 52.6% in clinically node positive (cN+) patients (including patients that received preoperative chemotherapy). In pN+ patients, the median metastatic focus size was 5mm. In cN0 patients, PET/CT rarely detected pN+ disease (sensitivity 7-23%) on a per patient or per region level regardless of chemotherapy status (Table 1). In cN+ patients, a negative PET/CT had utility in ruling out positive lymph node disease (sensitivity 92-100%, specificity 63-81%).
Conclusions: The primary role of 18F-FDG PET/CT prior to RC appears to be in adjudicating enlarged nodes identified by CT. Preoperative 18F-FDG PET/CT has limited utility in cN0 patients and thus should not be used routinely.
Source of Funding: This research was supported by the Sidney Kimmel Center for Prostate and Urologic Cancers and funded in part through the NIH/NCI Cancer Center Support Grant P30 CA008748.