Definitive radiotherapy in the management of node-positive bladder cancer: A National Cancer Data Base (NCDB) analysis.

394 Background: The survival impact of definitive radiotherapy (RT) in lymph node positive (N+) non-metastatic (M0) bladder cancer is unclear, as reflected in the National Comprehensive Cancer Network (NCCN) guideline recommendation for chemotherapy (CT) with or without RT in this population. We conducted the present analysis of the NCDB to determine whether RT at a definitive dose would be associated with improved overall survival (OS) in patients with N+ bladder cancer. Methods: NCDB was queried for subjects diagnosed from 1998-2012 with cN1-3 M0 cancer of the urinary bladder who did not undergo cystectomy. Definitive RT included external beam radiotherapy to the pelvis or bladder regions to a cumulative dose of ≥ 54Gy (per NCCN guideline for gross nodal disease). Cox regression was used to assess the association of definitive RT with overall survival while controlling for patient-related, tumor-related, and treatment-related factors. Results: 3,298 N+ subjects not undergoing cystectomy were identified, of whom 840 (25.5%) received any RT and 392 (11.9%) received ≥ 54Gy. In the entire cohort, multivariate analysis adjusting for age, year, sex, race, location, income, comorbidity, histology, grade, T-stage, N-stage, and receipt of chemotherapy demonstrated an OS benefit (HR for death 0.69; 95%CI 0.59-0.82; p < 0.01) with cumulative RT dose ≥ 54Gy. On subgroup analysis, this OS benefit persisted both among the 1905 patients (331 receiving ≥ 54Gy) undergoing CT (HR 0.66; 95%CI 0.46-0.95; p = 0.02) and among the 1393 patients (61 receiving ≥ 54Gy) not undergoing CT (HR 0.67; 95%CI 0.55-0.82; p < 0.01). Conclusions: In the largest analysis to date of definitive radiotherapy for N+ bladder cancer, receipt of a definitive RT dose was associated with improved OS, irrespective of receipt of CT. Intermediate oncologic endpoints including locoregional control and disease-free survival were unavailable for analysis. With a minority of N+ subjects receiving any radiotherapy, this intervention appears to be underutilized among these patients.