Diagnostic accuracy of preoperative lymph node staging of bladder cancer according to different lymph node locations: A multicenter cohort from the European Association of Urology - Young Academic Urologists.

Background: The preoperative lymph node (LN) staging of bladder cancer (BCa) addresses the subsequent therapeutic strategy and influences patient's prognosis. However, sparce evidence exists regarding the accuracy of conventional cross-sectional imaging, such as computed tomography or magnetic resonance imaging, in correctly detect LN status. We aimed to assess the diagnostic accuracy of conventional cross-sectional imaging in detecting preoperative LN involvement among BCa patients treated with radical cystectomy and pelvic lymph node dissection.

Methods: We retrospectively analyzed data of 1,104 patients who underwent preoperative LN staging with computed tomography or magnetic resonance imaging and subsequent radical cystectomy with pelvic lymph node dissection for BCa between 1997 and 2017 at three tertiary referral centers. Patients receiving neoadjuvant chemotherapy were excluded. We assessed the concordance between clinical (cN) and pathological LN (pN) status, defined as the accuracy of imaging in detecting LN involvement using pathological specimen as reference; concordance was expressed according to Cohen's kappa coefficient. Location-based sub-analyses were performed, distinguishing among external iliac, intern iliac, obturator, common iliac, presacral and paraaortic LNs.

Results: Among 870 cN0 patients, 68.9% were confirmed pN0 at pathological report; while among 234 cN+ patients, 50.5% were found with LN metastases at pathological specimen. Overall, conventional imaging showed slight concordance (64.9%) between cN and pN stages (sensitivity: 30%; specificity: 84%). At sub-analysis, no agreement between cN and pN status was found in each LN location, with the only exception of common iliac LNs with slight concordance (37.5%). Common iliac LNs achieved the highest sensitivity and positive likelihood ratio (15% and 2.4, respectively) compared to other LN locations.

Conclusions: Overall, preoperative cross-sectional imaging exhibited a slight concordance between cN and pN status. Our location-based sub-analyses showed unsatisfactory results in each LN location- Thus, nomograms combining morphological patterns with serological and clinicopathological features are urgently required.