Evaluation of the contribution of demographics, access to health care, treatment, and tumor characteristics to racial differences in survival of advanced prostate cancer.

BACKGROUND: Racial differences in prostate cancer (PCa) outcomes in the United States may be due to differences in tumor biology and race-based differences in access and treatment. We designed a study to estimate the relative contribution of these factors on Black/White disparities in overall survival (OS) in advanced PCa.

METHODS: We identified Black and White men aged ≥ 40 years with metastatic or locally advanced PCa (cN+ cM+ and/or T3/4) between 2004 and 2010 using the National Cancer Database. We employed sequential propensity score weighting procedures to generate simulated cohorts of Black and White patients with equal demographics, access to care, treatment, and tumor characteristics. Adjusted survival analyses were used to compare survival in these simulated cohorts. The changes in relative survival after each weighting procedure were used to infer the contribution of each set of variables on the excess risk of mortality in Blacks.

RESULTS: In total, 35,611 men met inclusion criteria, 5927 (16.77%) of whom were Black. Survival was significantly worse for Black men after adjusting for demographics and comorbidities (hazard ratio (HR) 1.27, 95%-confidence interval (95%-CI) 1.2-1.34, p < 0.001). After simulating equal access to care, there was no significant difference in survival between races (HR 1.04, 95%-CI 0.97-1.12, p = 0.276), despite worse tumor characteristics in Blacks. After simulating equal treatment and equivalent tumor characteristics, Black men had a better survival than Whites (HR 0.93, 95%-CI 0.86-1.01, p = 0.071 and HR 0.92, 95%-CI 0.84-1.00, p = 0.043, respectively). Overall, access-related variables explained 84.7% of the excess risk of death in Black men.

CONCLUSION: Our analysis of men with advanced PCa revealed worse OS among Blacks. However, when access to care, treatment, and cancer characteristics are accounted for, Black race was associated with better OS. These findings suggest that initiatives to improve access to care may represent an effective tool to reduce disparities in PCa outcomes.