Sociodemographic and survival disparities for histologic variants of bladder cancer.

Introduction: To investigate the impact of perioperative factors on overall survival among patients with histologic variants of bladder cancer treated with radical cystectomy.
Materials and Methods: The National Cancer Data Base was utilized to identify patients diagnosed with muscle-invasive bladder cancer (cT2-4, N0, M0) from 2004-2013. Variant histology bladder cancers (non-mucinous adenocarcinoma, mucinous/signet ring adenocarcinoma, micropapillary urothelial carcinoma, small cell carcinoma, and squamous cell carcinoma) were compared to urothelial carcinoma with respect to overall survival. Adjusted hazard ratios (aHR) and 95% confidence intervals (95% CI) were calculated from a multivariable Cox regression model to examine factors affecting overall survival, T upstaging, N upstaging, and positive surgical margins. Median survival was calculated using Kaplan-Meier analysis.
Results: A total of 5,856 patients were included in this study. Significant predictors of worse overall survival included: African-American ancestry (aHR = 1.24, 95%CI: 1.03-1.48, p = 0.021), age (1.03, 1.02-1.03, p < 0.001), comorbidity (1.30, 1.20-1.40, p < 0.001), cT3 stage (1.41, 1.26-1.57, p < 0.001), and cT4 stage (1.59, 1.38-1.84, p < 0.001). Small cell carcinoma (2.10, 1.44-3.06, p < 0.001) and non-mucinous adenocarcinoma (1.59, 1.15-2.20, p = 0.005) were significant predictors of worse overall survival compared to urothelial carcinoma. Small cell carcinoma had the worst 5 year overall survival (15.5%, 95% CI: 5.2%-30.9%) compared to urothelial carcinoma (48.7%, 95% CI: 47.2%-50.2%). Micropapillary urothelial carcinoma was a significant predictor of increased progression to node positivity and positive margin status after radical cystectomy compared to urothelial carcinoma (6.01, 3.11-11.63, p < 0.001; 4.38, 2.05-9.38; p < 0.001).
Conclusions: Among bladder cancer patients with equal treatment and staging, small cell carcinoma and non-mucinous adenocarcinoma variant histologies were predictive of worse overall survival compared to urothelial carcinoma. Patient demographics such as African-American ancestry and age were also predictive of worse overall survival among variant histology bladder cancer and urothelial carcinoma.