Topography and Lateralization of Nodal Metastases in Muscle-Invasive Bladder Cancer Using Super-Extended Pelvic Lymph Node Dissection with the Sentinel Lymph Node Technique.

Background: This study assessed the topography and lateralization of lymph node (LN) metastases in muscle-invasive bladder cancer (MIBC) patients using super-extended pelvic lymph node dissection (sePLND) with sentinel lymph node dissection (SLND). Methods: We analyzed 54 MIBC patients who underwent cystectomy with sePLND and SLND. Tumor location was classified using cystoscopy. Nanocolloid-Tc-99m was injected peritumorally. Preoperative SPECT/CT lymphoscintigraphy and an intraoperative gamma probe were used for SLN detection. Results: A total of 1414 LNs, including 192 SLNs, were resected from 54 patients. Metastases were found in 72 LNs from 22 patients (41%). The obturator fossa was the primary site for LN metastases (37.5%). SLNs were most common in the external iliac region (34.4%). In 36% of the patients with positive LNs, metastases were identified only through sePLND. In 9% of the patients, metastases were found solely in the pararectal region, identified through SLND. Tumor lateralization correlated with ipsilateral positive LNs, but 20% of the patients had contralateral metastases. Conclusions: The pararectal region may be the exclusive site for positive LNs in MIBC. The obturator fossa is the most prevalent region for LN metastases. Unilateral PLND should be avoided due to the risk of contralateral metastases. Combining sePLND with SLND improves staging.