Geographic Distribution of Racial Differences in Bladder Cancer Mortality in the United States: A Nationwide Population-Based Study

Abstract

African-Americans (AAs) have up to two times increased risk of bladder cancer death than Caucasians. Bladder cancer mortality increases exponentially once it invades the muscle. Geographic heterogeneity in bladder cancer mortality according to race remains to be determined. The purpose of this study was to determine the geographic distribution of muscle-invasive bladder cancer (MIBC) mortality according to race. Analysis of Surveillance, Epidemiology, and End Results (SEER)-Medicare data for 6,044 patients aged 66-85 diagnosed with clinical stage T2-T4 N0M0 bladder cancer from January 1, 2002 to December 31, 2011. Fine and Gray competing risks regression models, including an unadjusted model and an adjusted model with an interaction term between race and registry, were used to assess the association of race with bladder cancer-specific mortality (BCSM) according to tumor registry. Out of 6,044 patients, 5,408 (89.5%) were Caucasian, 352 (5.82%) were non-Hispanic AA, 85 (1.4%) were Hispanic, and 199 (3.29%) were other. Of the 18 registries, AAs with bladder cancer were largely concentrated in Louisiana (19%), New Jersey (17.9%) and Georgia (17.6%). New Jersey was the only registry where AAs had increased risk of BCSM than Caucasians and only for stage T2 disease: (AHR, 1.74; 95% CI 1.22-2.47, P=0.002). AAs in New Jersey had worse BCSM than Caucasians regardless of management: no curative treatment (AHR, 1.61; 95% CI 1.09-2.37, P=0.0168), radical cystectomy (AHR, 2.05; 95% CI 1.26-3.35, P=0.0039), and trimodal therapy (AHR, 1.55; 95% CI 1.03-2.35, P=0.0367). We observed geographic variation in death from bladder cancer which impacted one registry which had one of the largest population of AAs. These findings support further investigation into the social determinants of race (i.e. socioeconomic status and distance to health care facility) which may drive these results.