Abstract SY09-01: Increased colorectal cancer burden among African Americans: Access, utilization, or biology
Authors: Laiyemo Adeyinka O. 
Published: August 2012

It is unclear whether the disproportionately higher incidence of and mortality from colorectal cancer among blacks compared with whites reflects differences in three major domains: healthcare access, healthcare utilization or colorectal cancer susceptibility. Studies have suggested that blacks tend to present at late stages with colorectal cancer, have more proximal distribution of the disease and poorer survival. However, studies that incorporated socioeconomic factors such as household income, healthcare insurance and highest education attained have suggested a reduction in the observed disparities between blacks and whites.

It is well known that colorectal cancer screening rates are lower among blacks. This may be due to lower healthcare access, but studies have suggested that blacks tend to underutilize healthcare resources even when such services are covered benefits within the healthcare system they belong. This may be due to lack of health education or mistrust of the health system. Understanding the specific contribution of access, utilization and biology to colorectal cancer disparity by race is a major limiting step to designing an effective solution to this public health problem. Unfortunately, no study has evaluated this. Furthermore, most studies that have evaluated the uptake of colorectal cancer screening by race did not report the yield of colorectal neoplasia at screening and most studies that have reported racial differences in the risk of colorectal neoplasia have been limited by retrospective designs, non-screening populations, small sample sizes, single institution experience, and lack of histopathologic diagnosis.

The ongoing Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) provided an opportunity to evaluate two of these three domains (healthcare utilization and biology) within the same cohort of participants who underwent trial-sponsored screening flexible sigmoidoscopy (FSG) without biopsy at baseline in 10 geographically dispersed centers in the United States. There were 57,561 whites and 3,011 blacks who underwent FSG and provided information on their highest education attained (as a surrogate for socioeconomic status). We noted that blacks and whites were equally as likely to have an abnormal FSG in which a polyp or mass was found (25.5% versus 23.9%, P value = 0.257), but blacks were significantly less likely to undergo diagnostic colonoscopy up to one year subsequent to the abnormal FSG (RR = 0.88; 95% CI = 0.83 - 0.93). However, there were no material differences in the yield of adenoma, advanced adenoma, and colorectal cancer by race, among those who underwent diagnostic colonoscopy. This study was limited by the fact that FSG cannot evaluate proximal colon effectively and PLCO did not cover the cost of diagnostic tests. Nonetheless, it suggested that healthcare utilization may be playing more of a role in colorectal cancer disparities by race.

There is a need to increase access to colon cancer screening and improve health education of minorities through community based outreach efforts. This is expected to enhance the utilization of colorectal cancer healthcare resources by blacks. Optimal colon cancer screening uptake among blacks may subsequently uncover meaningful biological differences in colorectal cancer susceptibilities to guide screening recommendations.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr SY09-01. doi:1538-7445.AM2012-SY09-01