Effect of healthcare system on prostate cancer-specific mortality in African American and non-Hispanic white men.

Abstract

23 Background: Disparities in prostate cancer-specific mortality (PCSM) between African American and non-Hispanic White (White) patients have been attributed to biological differences; however, recent data suggest poorer outcomes may be related to barriers to medical care from the healthcare system in which patients receive care. We sought to evaluate potential drivers of disparities by comparing outcomes between African American and White men in the Surveillance, Epidemiology and End Results (SEER) national cancer registry and a relatively equal-access healthcare system, the Veterans Health Administration (VHA). Methods: We identified African American and White patients diagnosed with prostate cancer between 2004-2015 in the SEER and VHA databases. We analyzed metastatic disease at diagnosis with multivariable logistic regression, and PCSM with cumulative incidence analysis and sequential competing-risks regression adjusting for disease and sociodemographic factors. Results: The SEER cohort included 306,609 men (57,994 [18.9%] African American and 248,615 [81.1%] White) with a median follow-up of 5.3 years (interquartile range [IQR] 2.6-8.1 years), and the VHA cohort included 90,749 men (27,412 [30.2%] African American and 63,337 [69.8%] White) with a median follow-up of 4.7 years (IQR 2.4-7.6 years). In SEER, African American men were significantly more likely to present with metastatic disease (African American 4.3% versus White 3.0%, p< 0.001; multivariable odds ratio [OR] 1.25, 95% confidence interval [CI] 1.19-1.32, p< 0.001), whereas in the VHA, African American men were not significantly more likely to present with metastatic disease (African-American 3.2% versus White 3.3%, p= 0.26; multivariable OR 1.07, 95% CI 0.98-1.17, p= 0.12). In SEER, the 8-year cumulative incidence of PCSM was significantly higher for African American compared with White men (6.9% versus 5.1%, p< 0.001), whereas in the VHA, African American compared with White men did not have a significantly higher 8-year cumulative incidence of PCSM (5.5% versus 5.4%, p= 0.93). African American race was significantly associated with an increased risk of PCSM in SEER (univariable subdistribution hazard ratio [SHR] 1.39, 95% CI 1.33-1.45, p< 0.001), but was not significantly associated with PCSM on uni- and multivariable regression in the VHA. When adjusted for disease characteristics at diagnosis in SEER, disease extent, PSA, and Gleason score contributed to 85% of the risk of PCSM for African American men (adjusted SHR 1.06, 95% CI 1.02-1.12, p= 0.008). Conclusions: Racial disparities in PCSM were present in a national cohort, SEER, but not as pronounced in a relatively equal-access healthcare system, the VHA, potentially due to differences in metastatic disease at diagnosis among African American and White men between cohorts. These findings may be attributable to reduced barriers to care in the VHA.