MP55-18 ADJUVANT CHEMOTHERAPY AFTER RADICAL CYSTECTOMY FOR MUSCLE-INVASIVE BLADDER CANCER: A COMPARATIVE STUDY USING INVERSE-PROBABILITY-OF-TREATMENT WEIGHTING (IPTW)

INTRODUCTION AND OBJECTIVES: Inflammation plays an important role in the biology of many malignancies and is considered a hallmark of cancer. An elevated ratio of peripheral neutrophils to lymphocytes (NLR), a marker of host inflammation, has been associated with poor outcome in various solid tumors. We aimed to assess the association between pre-treatment NLR and survival in a large series of patients undergoing radical cystectomy (RC) for urothelial carcinoma of the bladder (UCB). METHODS: Patients undergoing RC for UCB between 19882012 were identified using our institutional RC database. NLR was computed using complete blood counts with differentials performed preRC, or prior to neo-adjuvant chemotherapy where applicable. Given the heterogeneity of cutpoints used in the literature, time dependent receiver operator characteristics (ROC) curves were used to determine the optimal cutpoint for predicting recurrence-free (RFS), cancer-specific (CSS) and overall survival (OS) among the range of values used in the existing literature. The predictive ability of NLR was then assessed using Kaplan-Meier analyses and multivariable Cox-proportional hazards models adjusting for age, gender, co-morbidity score, hemogloblin, platelet count, stage, surgical margin status, and receipt of neo-adjuvant or adjuvant chemotherapy. Lastly, the likelihood ratio test was used to determine if multivariable models were improved by the inclusion of NLR. RESULTS: Of the final cohort of 416 patients, median follow up was 58.4 months. There were 178 (42%) deaths overall, 110 (26%) UCB-related deaths, and 138 recurrences (33%). An NLR of 3 was determined as the optimal cut-off value for predicting survival outcomes based on the inflection point of the ROC curves. Patients with NLR 3 had significantly worse survival outcomes (5y-RFS: 53% vs. 64%, logrank p1⁄40.013; 5y-CSS: 57% vs. 75%, log-rank p<0.001; 5y-OS: 43% vs. 64%, log-rank p<0.001). Upon adjusting for patient and diseasespecific predictors, NLR 3 was significantly associated with worse RFS (HR1⁄41.79; 95%CI1⁄41.22-2.63, p1⁄40.003), CSS (HR1⁄41.94; 95% CI1⁄41.44-2.60, p<0.001) and OS (HR1⁄41.66; 95%CI1⁄41.23-2.25, p1⁄40.001). The likelyhood ratio test confirmed that prognostic models were improved by including NLR. CONCLUSIONS: NLR is an inexpensive prognostic biomarker for patients undergoing radical cystectomy for UCB. It offers pre-treatment prognostic value in addition to established patient and disease-related prognostic indicators, and may be helpful in guiding treatment decisions.