Optimizing pelvic lymph node dissection in bladder cancer: obturator focus, pN1 prognosis, and sentinel node...

To determine the optimal extent of pelvic lymph node dissection in bladder cancer, evaluating the prognostic relevance of nodal sub-staging, and assessing the feasibility of sentinel lymph node biopsy and omission of contralateral dissection.

This retrospective study included 180 patients undergoing laparoscopic or robot-assisted radical cystectomy. Sentinel lymph node detection was assessed in 30 cases as a pilot. The obturator region was defined according to lymphatic drainage patterns. The prognostic impact of nodal sub-staging was evaluated using Kaplan-Meier and Cox proportional hazards models. Laterality of tumor location and node metastasis was also analyzed.

Sentinel lymph node biopsy demonstrated a 63% detection rate with a 1.6% false-negative rate. Nodal metastases were observed in 8.9% of pN1 and 8.3% of pN2-3 cases, predominantly in the obturator region (87.5% and 100%, respectively). Lymph node metastases were most frequently located in the obturator region, including 87.5% of stage pN1 and 100% of stage pN2-3 cases. Cancer-specific survival was significantly better in pN1 than in pN2-3 cases (median 61 vs. 7 months, p < 0.001). Cox proportional hazards regression models identified pN2-3 as the strongest prognostic factor (HR for CSS: 25.4). Ipsilateral nodal metastasis was observed in 87.5% of lateral wall tumors.

Although sentinel lymph node biopsy demonstrated limited utility, the obturator region appears to represent the optimal diagnostic target for nodal metastasis. In pN1 disease, this region may be therapeutic, resembling sentinel nodes and showing limited spread with better prognosis than pN2-3 disease.