Do African American patients treated with radical cystectomy for bladder cancer have worse overall survival? Accounting for pathologic staging and patient demographics beyond race makes a difference
Background: It is estimated that 74,000 men and women in the United States will be diagnosed with bladder cancer and 16,000 will die from the disease in 2015. The incidence of bladder cancer in Caucasian males is double that of African American males, but African American men and women have worse survival. Although factors contributing to this disparity have been analyzed, there is still great uncertainty as to why this disparity exists. Objective: To evaluate whether the disparities in bladder cancer survival after radical cystectomy for transitional cell carcinoma (TCC) of the bladder amongst African American (AA) and Caucasian patients is attributable to patient demographics, year of diagnosis, and/or tumor characteristics. Methods: Using Surveillance, Epidemiology, and End Results Program (SEER) data from 1973-2011, African American and Caucasian patients treated with a radical cystectomy for TCC of the bladder were identified. Primary outcomes were all-cause and cancer-specific mortality. Differences in survival between African Americans and Caucasian patients were assessed using chi-square tests for categorical variables and Student's t-tests for continuous variables. Cox proportional hazards regression was used to measure the hazard ratio for African Americans compared to Caucasians for all-cause and cancer-specific mortality. In addition, coarsened matching techniques within narrow ranges, were used to match African American and Caucasian patients on the basis of age, sex, and cancer stage. Following matching, differences in all-cause and cancer-specific mortality were again assessed using a stratified Cox proportional hazards model, using the matching strata for the regression strata. Results: The study cohort consisted of 21,406 African American and Caucasian patients treated with radical cystectomy for bladder urothelial cancer, with 6.2% being African American and 73.9% male. African American patients hadworse all-cause and cancer-specific mortality in the univariable analysis (all-cause: HR: 1.23; 95% CI 1.15-1.32, p < 0.001); bladder-cancer specific: HR 1.21; 95% CI 1.11-1.33; p < 0.001). However, after accounting for sex, age, year of diagnosis, marital status, region of treatment, and stage at cystectomy, all-cause mortality was significant (HR 1.20; 95% CI 1.12-1.29; p < 0.0001), but not bladder-cancer specific mortality (HR 1.09; 95% CI 1.00-1.20; p < 0.053). Predictors of bladder cancer specific mortality were age, sex, stage of disease, and marital status. The matched analysis yielded a roughly 1 : 15 match, with 22,511 Caucasians being matched to 1,509 African American patients. In the matched analysis, African Americans had increased all-cause mortality (HR 1.17; 95% CI 1.09-1.26; p < 0.0001), but bladder-cancer specific mortality was no longer significant (HR 1.08; 95% CI 0.99-1.18; p < 0.102). Conclusions: African Americans who undergo a cystectomy are more likely to die, but not necessarily solely because of bladder cancer. Although African American patients have worse all-cause and cancer-specific mortality in univariable models, after controlling for sex, age, year of diagnosis, marital status, region of treatment, and stage at cystectomy, African American patients still have worse overall survival, but equivalent bladder-cancer specific survival. Differences in age, sex, and stage at diagnosis explain some, but not all of the differences in survival.
