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789 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.

478 Accuracy of FDG PET-CT compared with conventional CT for the lymph node staging in muscle invasive bladder cancer: Prospective study of 58 patients with extended lymphadenectomy

71.7%, pathology assistant 79.8%; p 0.84). Number of cases grossed did not correlate with either documenting the status of the perivesicular fat (quartile 4 73.6%, quartiles 1-3 76.9%; p 0.25) or the presence of fat invasion being corroborated microscopically (OR 0.99, 95% confidence interval: 0.97-1.02). CONCLUSIONS: A substantial proportion of cases at our institution do not have the gross impression of perivesicular fat invasion documented, which is necessary for pT3 substaging in bladder cancer. Improved assessment of fat invasion impacted substaging and may be a useful quality indicator. Understanding variables that impact pT3 staging could help account for differences in survival between institutions.