Decreasing Black-White Disparities in Colorectal Cancer Incidence and Stage at Presentation in the United States

Abstract

Background: There are long-standing black-white disparities in colorectal cancer incidence and outcomes in the United States. Incidence and stage at diagnosis reflect the impact of national efforts directed at colorectal cancer prevention and control. We aimed to evaluate trends in black-white disparities in both indicators over four decades to inform the future direction of prevention and control efforts.Methods: We used Surveillance, Epidemiology, & End Results (SEER) data to identify whites and blacks with histologically confirmed colorectal cancer from January 1, 1975 through December 31, 2012. We calculated the age-adjusted incidence and the proportion of cases presenting in late stage by race and year. We then calculated the annual percentage change (APC) and average APC for each indicator by race, examined changes in indicators over time, and calculated the incidence disparity for each year.Results: There were 440,144 colorectal cancer cases from 1975 to 2012. The overall incidence decreased by 1.35% and 0.46% per year for whites and blacks, respectively. Although the disparity in incidence declined from 2004 to 2012 (APC = -3.88%; P = 0.01), incidence remained higher in blacks in 2012. Late-stage disease declined by 0.27% and 0.45% per year in whites and blacks, respectively. The proportion of late-stage cases became statistically similar in whites and blacks in 2010 (56.60% vs. 56.96%; P = 0.17).Conclusions: Black-white disparities in colorectal cancer incidence and stage at presentation have decreased over time.Impact: Our findings reflect the positive impact of efforts to improve colorectal cancer disparities and emphasize the need for interventions to further reduce the incidence gap. Cancer Epidemiol Biomarkers Prev; 26(5); 762-8. ©2016 AACR.

Figure 1

Evaluation for significant linear trends in CRC incidence in whites and blacks, SEER 9 (1975–2011)* *Rates are per 100, 000 and age-adjusted to the 2000 U.S. standard population. APC indicates annual percentage change. ^ indicates the APC is significantly different from zero at p = 0.05

Figure 2

Evaluation for significant trends in the absolute difference in CRC incidence between whites and blacks; SEER 9 (1975–2011)* *Observed difference is defined as the absolute difference in the incidence in whites and the incidence in blacks for a given year. APC indicates annual percentage change. ^ indicates the APC is significantly different from zero at p = 0.05

Figure 3

Evaluation for significant linear trends in late stage CRC presentation in whites and blacks; SEER 9 (1975–2011)* *APC indicates annual percentage change. ^ indicates the APC is significantly different from zero at p = 0.05.