Disentangling Racial, Ethnic, and Socioeconomic Disparities in Treatment for Colorectal Cancer

Background: Colorectal cancer is curable if diagnosed early and treated properly. Black and Hispanic patients with colorectal cancer are more likely to experience treatment delays and/or receive lower standards of care. Socioeconomic deprivation may contribute to these disparities, but this has not been extensively quantified. We studied the interrelationship between patient race/ethnicity and neighborhood socioeconomic status (nSES) on receipt of timely appropriate treatment among patients with colorectal cancer in California. Methods: White, Black, and Hispanic patients (26,870) diagnosed with stage I-III colorectal cancer (2009-2013) in the California Cancer Registry were included. Logistic regression models were used to examine the association of race/ethnicity and nSES with three outcomes: undertreatment, >60-day treatment delay, and >90-day treatment delay. Joint effect models and mediation analysis were used to explore the interrelationships between race/ethnicity and nSES. Results: Hispanics and Blacks were at increased risk for under-treatment [Black OR = 1.39; 95% confidence interval (CI) = 1.23-1.57; Hispanic OR = 1.17; 95% CI = 1.08-1.27] and treatment delay (Black/60-day OR = 1.78; 95% CI = 1.57-2.02; Hispanic/60-day OR = 1.50; 95% CI = 1.38-1.64) compared with Whites. Of the total effect (OR = 1.15; 95% CI =1.07-1.24) of non-white race on undertreatment, 45.71% was explained by nSES. Conclusions: Lower nSES patients of any race were at substantially higher risk for undertreatment and treatment delay, and racial/ethnic disparities are reduced or eliminated among nonwhite patients living in the highest SES neighborhoods. Racial and ethnic disparities persisted after accounting for neighborhood socioeconomic status, and between the two, race/ethnicity explained a larger portion of the total effects. Impact: This research improves our understanding of how socioeconomic deprivation contributes to racial/ethnic disparities in colorectal cancer.