3208 - Mapping Patterns of Pelvic Lymph Node Metastasis in Bladder Urothelial Carcinoma Stratified by T-Stage and G-Grade: Implications for Personalized Pelvic Radiotherapy

Purpose/Objective(s): To evaluate the association between primary bladder urothelial carcinoma T-stage, G-grade, and pelvic lymph node metastasis (PLNM), and to delineate the location of metastatic pelvic lymph nodes across different T-stage and G-grade combinations.

Materials/Methods: We collected and analyzed surgical and pathological data from 1,555 patients who underwent radical cystectomy with pelvic lymph node dissection for bladder urothelial carcinoma at Peking University First Hospital between October 2014 and September 2024. Pelvic lymph nodes were anatomically classified into six regions: peri-vesical, internal iliac/obturator, external iliac, presacral, common iliac, and para-aortic. Descriptive statistics were used to quantify PLNM rates and distribution patterns by T-stage and G-grade. Multivariate logistic regression identified independent predictors of PLNM.

Results: Pelvic lymph node metastasis was identified in 19.1% (297/1,555) of patients, involving 946 metastatic lymph nodes. Stratified by T-stage, PLNM rates progressively increased from 2.6% in Ta/Tis/T1 tumors to 11.0% in T2, 29.8% in T3, and 50.0% in T4 tumors. Similarly, G-grade stratification revealed no lymph node involvement in G1 tumors (0%), whereas PLNM rates rose to 2.9% in G2 and 23.9% in G3 tumors. Notably, among T2G3, T3G3, and T4G3 patients with lymph node metastasis, 96.9%, 93.6%, and 84.9% of patients had metastases exclusively below the iliac bifurcation, whereas 100%, 95.7%, and 95.9% had metastases exclusively below the aortic bifurcation, respectively. Multivariate logistic regression confirmed T-stage (OR=3.12, 95% CI:2.67–3.65; P<0.01) and G-grade (OR=10.42, 95% CI:5.31–20.48; P<0.01) as independent predictors of PLNM, with no significant associations observed for age, sex, or tumor size.

Conclusion: PLNM rates in bladder urothelial carcinoma significantly correlate with advancing T-stage and G-grade. Importantly, distinct probabilities of PLNM and spatially heterogeneous distribution patterns were identified across T-stage and G-grade subgroups. These findings may be able to provide some data support to achieve personalized pelvic irradiation for bladder urothelial carcinoma in the future.