FDG PET-CT for Lymph Node Staging of Bladder Cancer: A Prospective Study of Patients with Extended Pelvic Lymphadenectomy

Background:

The purpose of this study was to evaluate the diagnostic accuracy of [18F] fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) for lymph node (LN) staging of bladder cancer patients undergoing radical cystectomy (RC) with extended pelvic lymphadenectomy compared to conventional CT.

Methods:
A total of 61 patients underwent FDG PET-CT before RC and extended pelvic lymphadenectomy. A template for extended pelvic lymphadenectomy to the level of the inferior mesenteric artery was divided into 11 anatomic nodal packets. Definitive pathologic findings of resected LNs were correlated with the results of FDG PET-CT and CT alone in a patient- and nodal packet-based manner.

Results:
Among the 61 patients, pathological staging confirmed LN metastasis in 17 patients (27.9 %). In total, 627 LN packets (2580 LNs) were resected and histologically evaluated. The mean number of LNs removed was 42 (median 40; range 22-118). Of the 627 LN packets removed, 27 packets (4.3 %) were positive for LN metastasis based on pathologic analysis. On a patient-based analysis, FDG PET-CT and conventional CT showed a sensitivity of 47.1 and 29.4 %, respectively, specificity of 93.2 and 97.7 %, respectively, positive predictive value (PPV) of 72.7 and 78.2 %, respectively, and negative predictive value (NPV) of 82.0 and 78.2 %, respectively. On a nodal packet-based analysis, sensitivity, specificity, PPV, and NPV were 14.8, 97.8, 23.5, and 96.2 %, respectively, for PET-CT and 11.1, 98.7, 27.3, and 96.1 %, respectively, for conventional CT.

Conclusions:
Combined FDG PET-CT did not improve the diagnostic accuracy of conventional CT for the detection of LN metastasis in bladder cancer patients scheduled for RC.