Lymph Node Yield at Radical Cystectomy Predicts Mortality in Node-negative and not Node-positive Patients

Abstract

To better define the relationship between lymph node count and survival in patients undergoing radical cystectomy for bladder cancer by identifying and controlling for key confounding variables in a large population-based cohort. Considerable controversy remains regarding the correlation between node count and survival, and most prior analyses have not accounted for both patient and provider factors. The Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database was used to identify patients with urothelial bladder carcinoma who underwent radical cystectomy from 1992 to 2006. Patients were divided into 2 cohorts based on the presence or absence of nodal metastases, and we performed Cox regression analyses to evaluate the association between node count and survival. Covariates included age, Charlson comorbidity index, stage, grade, lymph node density, number of positive nodes, urinary diversion, chemotherapy, year of surgery, transfusion, and surgeon volume. The cohort consisted of 2391 node-negative and 779 node-positive patients. In node-negative patients, individuals with low node counts had significantly worse overall survival (OS) and disease-specific survival (DSS) compared to the highest node count tertile. In node-positive patients, node count was not an independent predictor of OS or DSS. Lymph node count at radical cystectomy is associated with both OS and DSS in patients without nodal metastases. However, in patients with node-positive disease, node count is not an independent predictor of survival suggesting that it is likely a proxy for other patient and provider factors in these individuals.