PURPOSE

Structural racism (SR) is a potential driver of health disparities, but research quantifying its impacts on cancer outcomes has been limited. We aimed to develop a multidimensional county-level SR measure and to examine the association of SR with breast cancer (BC) treatment delays among Black and White patients.

METHODS

The cohort included 32,095 individuals from the North Carolina Central Cancer Registry with stage I to III BC diagnosed between 2004 and 2017 and linked to multipayer insurance claims from the Cancer Information and Population Health Resource. County-level data were drawn from multiple public sources aggregated in the Robert Wood Johnson County Health Rankings database. Racial gaps in eight social determinants across five domains were quantified at the county level and ranked on a 0-100 minimum-maximum scale. Domain scores were averaged to create a SR Composite Index (SRCI) score. We used multilevel logistic regression with random intercepts and multiple cross-level interaction terms to evaluate the association between county-level SRCI and patient-level treatment delays, adjusting for patient-level characteristics and stratified by race.

RESULTS

The SRCI score ranged from 21 to 75 with a median (IQR) of 39.0 (31.8, 45.7). For Black patients, a 10-unit increase in SRCI score was associated with increased odds of delay (Adjusted odds ratios [aOR], 1.25; 95% confidence limits [CL], 1.08 to 1.45). No such association was found for White patients (OR, 1.05; 95% CL, 0.97 to 1.15).

CONCLUSION

Area-level SR measured by a composite index is associated with higher odds of BC treatment delays among Black, but not White patients. Increasing county-level SR is associated with increasing Black-White disparities in treatment delay. Further research is needed to refine the measurement of SR and to examine its association with other cancer care disparities.