Pelvic Lymph Node Dissection may be Limited on the Contralateral Side in Strictly Unilateral Bladder Cancer without Compromising Oncological Radicality.

Results of a dynamic multimodality mapping study showed no lymphatic drainage of the lateral bladder wall to the contralateral internal iliac region. To validate whether pathoanatomical mapping in bladder cancer (BC) patients can confirm these results. Between 01/2000 and 07/2013, 825 BC patients preoperatively staged ≥pT1 and without clinical signs of metastases (cN0 cM0) underwent extended pelvic lymph node dissection (ePLND) and radical cystectomy at our department. Of these patients, 23% (193/825) were lymph node (LN) positive in the pathological specimen; 26% (51/193) of this subgroup had strictly unilateral BC. Pathoanatomical mapping was used to retrospectively validate the distribution of LN involvement in these 51 patients. A median of 35 LNs were removed per patient (range: 13-80 LNs), with a median of 2 positive LNs (range: 1-14 LNs). 27% (14/51) of patients presented with LN metastases on the contralateral side. No positive LNs were found in the contralateral internal iliac region or the contralateral fossa of Marcille. 10% (5/51) of patients had LN metastases only on the contralateral side without evidence of metastases on the tumor-bearing side. Our findings corroborate the data of a dynamic mapping study showing bilateral lymphatic drainage in almost one third of patients with strictly unilateral BC, but no lymphatic drainage from the lateral bladder wall to the contralateral internal iliac region. If prospective studies confirm these results, the contralateral internal iliac region may be omitted during ePLND in patients with strictly unilateral BC