UCLA

African Americans are disproportionately impacted by colorectal cancer (CRC) with higher incidence of disease, higher mortality from disease, and poorer disease survival. These disparities are likely the result of multiple factors, including a high prevalence of CRC risk factors, unfavorable tumor biology, and poor access to medical services among blacks. In addition, while national guidelines promote universal screening for CRC in all Americans, African Americans are less likely than white Americans to pursue screening. There is increasing emphasis in health services research to understand why CRC screening is underutilized in African Americans and to develop interventions that improve screening uptake in the racial subgroup.

This dissertation consists of three distinct but related studies that explore black-white disparities in CRC incidence, screening, and outcomes in the United States. The first study evaluates trends in black-white disparities in CRC incidence and stage at diagnosis over the past four decades using the Surveillance, Epidemiology, & End Results (SEER) cancer registry database. Study two is a systematic review of the literature evaluating barriers to colonoscopic CRC screening in African Americans. Study three is a retrospective analysis to compare rates of colonoscopic screening in African Americans and non-African Americans and to identify patient-level, provider-level, and system-level factors associated with receipt and non-receipt of screening in a large Veteran Affairs Healthcare Network.

The dissertation demonstrates that while disparities in both CRC incidence and late stage presentation have narrowed over the past four decades, an incidence gap persists. The findings highlight the success of CRC prevention and early detection tools that have come into use over the past three decades and emphasize a continued need for strategies to improve uptake of CRC screening in African Americans. In addition, the dissertation identifies several patient-, provider-, and system-level factors that hinder colonoscopic screening in blacks and contribute to the incidence disparity. While future efforts to address disparities in CRC incidence should focus on increasing the use of screening endoscopy among African Americans to reduce disease incidence, we must not rely on colonoscopic screening alone to decrease the overall burden of CRC on blacks. By determining programs, policy, and interventions to reduce lifestyle risk factors for CRC and optimize use of both preventive and early detection screening methods in varied clinical settings, we can further reduce black-white disparities in CRC incidence, screening, and outcomes.