Abstract
Colorectal cancer (CRC) is the second leading cause of cancer death in the United States and an estimated 49,700 Americans will die of the disease in 2015. Blacks and people of low socioeconomic status bear a particularly disproportionate share of this burden, and this gap has persisted for decades. Evidence supports the hypothesis that disparities in death from CRC for blacks and low-income patients stem from lower utilization of health care services rather than higher biological risk. For instance, prognostic biomarkers in CRC tumors have been found to be similar or even more favorable in blacks compared to those of whites, yet blacks have higher mortality after diagnosis among patients with the same disease stage. Unfortunately, blacks are more likely to have advanced or disseminated tumors at the time of diagnosis. The evidence strongly suggests that these disadvantages for blacks in CRC outcomes (higher disease risk, advanced stage, and death) are the result of cumulative disparities along the CRC care continuum, particularly the receipt and quality of screening.
Increasing uptake of screening in the United States over recent decades has averted an estimated one-half of a million new CRC cases between 1987 and 2010. Microsimulation studies have found that an estimated 63% of CRC deaths in 2010 were attributable to non-receipt of screening, and increasing screening uptake to 80% by 2018 in the United States could reduce CRC incidence by 17% and death by 19%. These statistics underscore the potential gains from increasing uptake of screening. However, people from low-income backgrounds have half the rate of screening of high-income groups. Thus, effective strategies to increase screening uptake in low-income and minority populations is critical to advance the public health goal of eliminating CRC disparities.
Blacks have lower screening rates, are less likely to return for diagnostic testing when positive, and have lower quality of bowel preparation at the time of endoscopy. A poor quality test, failure to receive diagnostic testing after a positive screen, or failure to receive treatment for detected cancers is consequential and undermines the benefits of screening. Thus, increasing screening uptake along with improving the quality of screening are critical to eliminate disparities.
The goal to increase screening uptake will be undermined if screening is not affordable or easy to understand. Cost and ambiguities in the choice of screening tests are key barriers to receive quality screening for disadvantaged populations. It is unclear how screening tests and recommendation for testing could be tailored to the needs of blacks and low-income patients, complicating clinical decision-making on how screening should be offered. A particular issue facing beneficiaries of Centers for Medicare and Medicaid Services (CMS) is the requirement for cost-sharing. While the Affordable Care Act mandates coverage without cost-sharing, the Balanced Budget Act of 1997 specifically disallows CMS from waiving the 20-25% coinsurance when a diagnostic procedure such as biopsy or polypectomy is performed during the course of a screening colonoscopy, or if colonoscopy is performed because of a positive result on another screening test. These provisions may exacerbate disparities for low-income patients for whom such cost may be prohibitive and compound opportunity costs associated with undergoing colonoscopy due to time off work for both the patient and the accompanying adult.
Thus, there are many areas of uncertainty in the evidence on the most effective levers to reduce disparities for blacks. A stronger evidence base is needed to enable screening for blacks and low-income populations in the community as well as in healthcare settings. These include gaps in knowledge about: 1) whether blacks or African Americans who are at high risk are accurately identified and receive appropriate targeted screening based on their disease risk; 2) which population health approaches will be effective for screening minorities without relying exclusively on having a face-to-face encounter with health care professionals; 3) assuring adherence to screening for both colonoscopy and stool-based tests in community settings; 4) assuring that disadvantaged patients receive the highest quality of screening; 5) assuring receipt of follow-up testing when positive; 6) assuring receipt of treatment when diagnosed with cancer; and 7) assuring receipt of surveillance testing for those diagnosed with adenoma or high risk.
An approach to disparities research that addresses the continuum of cancer screening is necessary to enable progress and should include trans-disciplinary research teams to conduct research from implementation to precision science. Because the average age of people dying of CRC is 73 years and the majority of CRC deaths (70%) are in people who are Medicare age-eligible, there are substantial gains to be realized from focusing attention on CMS beneficiaries and the government's role. Such an effort will require many stakeholders.
Citation Format: Chyke A. Doubeni. Colorectal cancer disparities: Opportunities in the screening continuum. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr IA15.
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