Tumor Laterality Predicts Pelvic Lymph Node Metastasis Patterns in Bladder Cancer

Although lymph node involvement (LNI) is a critical prognostic factor guiding adjuvant therapy, randomized trials have failed to show a survival advantage of extended versus standard pelvic lymph node dissection (PLND) but have demonstrated increased morbidity. Refining PLND templates according to tumor characteristics, such as laterality, may improve the risk-benefit balance. This study aimed to clarify the relationship between bladder tumor location and the anatomical distribution of LNI in bladder cancer.

We retrospectively reviewed 102 patients who underwent radical cystectomy with bilateral extended PLND at Kyushu University Hospital between 2013 and 2024. Tumor laterality was classified as unilateral or bilateral. LNI sites were categorized as ipsilateral versus contralateral and by level (I: obturator, internal/external iliac; II: common iliac, presacral).

Overall, 17.6% of patients had LNI. Bilateral tumors were associated with higher nodal metastasis than were unilateral tumors (24.2% vs. 14.5%). In unilateral tumors, contralateral LNI without ipsilateral involvement occurred in only 1.5% of cases. Level II metastasis was uncommon (5.9%), and skip metastasis to level II nodes without level I involvement was rare (1.0%).

Tumor laterality is a strong predictor of nodal distribution. The rarity of contralateral or skip metastasis warrants prospective studies to validate tailored, tumor location-based PLND strategies.