Five-year Survival Stratification Using “the Cancer of the Bladder Risk Assessment” (COBRA) Score for Micropapillary and Sarcomatoid Urothelial Carcinoma of the Bladder Variants.

e16534 Background: The Cancer of the Bladder Risk Assessment (COBRA) score is a validated risk stratification tool for patients with urothelial carcinoma of the bladder (UCB) after cystectomy. Radical cystectomy with or without neoadjuvant chemotherapy is the standard of care for patients with muscle-invasive bladder cancer (MIBC). Lymph node density and the presence of positive lymph nodes have been demonstrated to be critical prognostic tools. Our goal was to evaluate 5-year overall survival (OS) on UCB variants: micropapillary and sarcomatoid, stratified by COBRA score and the presence of lymph nodes. Methods: We sampled the National Cancer Database (NCDB) for bladder cancer patients diagnosed with de novo micropapillary and sarcomatoid UCB between 2004 and 2018 and treated with radical cystectomy. 5-year Kaplan-Meier survival plots were utilized to assess OS differences amongst different COBRA score groups and stratified by the presence of lymph nodes (LNs). A multivariable Cox regression model was used to compare hazard ratios, adjusting for significantly unbalanced factors. A p-value < 0.05 was considered statistically significant. Results: A total of 1382 patients met the inclusion criteria. The average age was 68.10 + 10.31 years. 75% were male. Micropapillary represented 50.1% of selected histologies, followed by 49.5% sarcomatoid. For all combined histologies, 5-year OS percentage for patients with cystectomy and stratified by COBRA score (0-7) were 66% COBRA 0, 54% COBRA 1, 34% COBRA 2, 29% COBRA3, 15% COBRA > 4) (p < 0.001). 5-year OS for patients with cystectomy stratified by LN status was 54% for LN negative and 24% for LN positive (p < 0.001). Substratification of the cohort according to the presence of LNs and COBRA score have shown a numerical drop in 5-year survival and a notable decrease in median survival amongst compared groups. The risk of death was almost 5 times higher in patients with a high COBRA score (> 4) than in patients with a COBRA score of 0 (HR = 5.15, p < 0.001). Conclusions: COBRA score could contribute to clinical decision-making as a risk stratification tool for patients with UCB variants, micropapillary and sarcomatoid. 5-year OS decreases with higher COBRA scores, and LN status plays a major role in 5-year OS for these two UCB variants.[Table: see text]