Lymph node density for stratification of survival outcomes with node positive upper tract urothelial carcinoma

Introduction: The use of lymph node density (LND) as a predictor of survival outcomes has been studied with urothelial carcinoma of the bladder. Similar results can be postulated to upper tract urothelial carcinoma (UTUC). This study aims to determine the overall survival of patients with lymph node positive UTUC based on LND, utilizing the National Cancer Database (NCDB). Materials and methods: Data was derived from NCDB Participant User Kidney Dataset using the histology code 'transitional cell carcinoma', utilizing pN+ patients from 2004-2015. LND was calculated as number of positive nodes divided by total number of nodes removed. Patients were stratified by traditional AJCC pN stage and compared to LND groups (<30%, >= 30%). Primary outcome was overall survival. Kaplan-Meier and Cox regression analyses were performed. Results: A total of 2049 patients were identified (pN1=1022,pN2 = 1027; LND <30% = 370, >= 30%=1679). Mean LND was 71%. Cox regression for mortality using pN stage was not significant (p = 0.11); however, Cox regression for mortality using LND group noted significantly worsened survival with LND >= 30% (HR 1.54, p = 0.001). Kaplan Meier analysis for overall survival at 2 years showed no difference between pN1 and pN2 stages (35.3% versus 34.1%; log rank p = 0.37). Kaplan Meier analysis for overall survival at 2 years revealed significant difference between LND groups (LND < 30%, 47.3% versus LND >= 30%, 32.0%; log rank p < 0.001). Conclusions: LND provides improved prognostic information regarding overall survival, compared to traditional AJCC pN staging. Future studies need to evaluate LND to improve prognostic understanding of lymph node positive UTUC.