Assessing the impact and lag time of racial disparities in colorectal cancer screening on disparities in mortality

Background: Colorectal cancer is the third most common cancer cause of death in America. Blacks have disproportionately higher mortality rates of any racial group in the U.S. There has been a divergence in colorectal cancer mortality rates between Whites and Blacks due to earlier and larger reductions of mortality in Whites. Colorectal cancer mortality rates have decreased for each stage in both races, but the stage-specific decreases were smaller in Blacks, particularly in distant-stage disease. This results in an increase in racial disparity for each stage of disease. We are interested in assessing impact and lag time of screening disparities on mortality disparities. Methods: This analysis uses state-level 1999-2009 screening data from Behavioral Risk Factor Surveillance System and incidence and mortality data from the National Program of Cancer Registries. The risk difference between Blacks and Whites was calculated for screening, incidence, and mortality rates by state. Data is summarized with descriptive statistics. Time series analysis was conducted to identify lag time between screening and mortality and assess the impact of screening disparities on mortality disparities. Results: In all 26 states with complete data, Blacks had higher mortality rates while Whites had higher screening rates. The trend continues with incidence rates, except for New York, where Whites had a higher incidence of colorectal cancer. Conclusions: These results have major implications for health policy. Understanding the lag time and impact of colorectal cancer screening disparities on mortality disparities will be useful in the development of goals and targets for primary prevention programs.