Racial Disparities in Colon Cancer Survival: A Propensity Score Matched Analysis in the United States

Background: Black patients are disproportionally impacted by colorectal cancer, both with respect to incidence and mortality. Studies accounting for patient- and community-level factors that contribute to such disparities are lacking. Our objective is to determine if Black compared to White race is associated with worse survival in colon cancer, while accounting for socioeconomic and clinical factors.

Methods: A retrospective analysis was performed of Black or White patients with nonmetastatic colon cancer in the Surveillance, Epidemiology, and End Results cancer registry between 2008 and 2016. Multivariable Cox regression analysis and propensity-score matching was performed.

Results: A total of 100,083 patients were identified, 15,155 Black patients and 84,928 White patients. Median follow-up was 38 months (interquartile range: 15-67). Black patients were more likely to lack health insurance and reside in counties with low household income, high unemployment, and lower high school completion rates. Black race was associated with poorer unadjusted 5-year cancer-specific survival (79.4% vs 82.4%, P < .001). After multivariable adjustment, Black race was associated with greater 5-year cancer-specific mortality (hazard ratio: 1.19, 95% confidence interval: 1.13-1.25, P < .001) and overall mortality (hazard ratio: 1.12, 95% confidence interval: 1.08-1.16, P < .001). Mortality was higher for Black patients across stages: stage I (hazard ratio: 1.08, 95% confidence interval: 1.08-1.09), stage II (hazard ratio: 1.06, 95% confidence interval: 1.06-1.07), stage III (1.03, 95% confidence interval: 1.03-1.04). Propensity-score matching identified 27,640 patients; Black race was associated with worse 5-year overall survival (67.5% vs 70.2%, P = .003) and cancer-specific survival (79.4% vs 82.3%, P < .001).

Conclusions: This US population-based analysis confirms poorer overall survival and cancer-specific survival in Black patients undergoing surgery for nonmetastatic colon cancer despite accounting for trans-sectoral factors that have been implicated in structural racism.