Breaking through outdated structures in disease risk and prognosis with multimodal approaches

Colorectal cancer (CRC) is a disease whose course and its outcomes are also determined by socioeconomic (SE) and ethnic factors. A recent study investigates how these inequalities could be most effectively addressed.

Ethno-socioeconomic differences in colorectal cancer matter

Colorectal cancer (CRC) is a disease whose course and its outcomes are also determined by socioeconomic (SE) and ethnic factors. A recent study by John M. Carethers from the Department of Gastroenterology at the University of Michigan in Ann Arbor, USA, and C.A. Doubeni from the Center for Health Equity and Community Engagement Research at the Mayo Clinic in Rochester, Minnesota, USA, investigates how these inequalities could be most effectively addressed.¹

Frequency and prognosis of CRC still influenced by ethno-socioeconomic factors

The authors first tackled the significance of ethno-socio-economic differences in the CRC. For example, among African-Americans (AA) aged between 20 and 44 years, a CRC incidence of 7.9 / 100,000 was observed, while US-born non-Hispanic white (NHW-US) Americans have an incidence of 6.7 / 100,000 and Asian or Pacific Island (API) Americans have a frequency of 6.3 / 100,000.¹

The 5-year survival rate of AAs in the USA is 7% lower for systemic CRC (58%) than for NHW-US, as well as for regional diseases (65% in AAs vs. 72% in NHW), and is still 4%  lower for localized diseases in AAs than for NHW (86% in AAs vs. 90% in NHW).¹ Although all ethnic groups in the USA have seen a decrease in CRC mortality, relative inter-ethnic differences have remained unchanged over the past 25 years.¹

Although this assumption has not yet been substantiated by their own studies, the authors suggest that CRC-related health inequalities due to socioeconomic differences are mainly the result of cumulative disadvantages in health behavior and access to health services. In their view, however, temporary restrictions are unlikely to help explain the observed disadvantages of socioeconomically worse-off populations.

Socio-economic factors influencing CRCs

Among the socioeconomic factors influencing CRCs are:

• Significantly lower participation in screening studies: People with a low level of education and/or low income take advantage of such examinations much less often. These factors alone explain 42% of the observed CRC incidence differences between AAs and NHWs and 19 of the mortality difference between the two groups.²
• The poorer access to health services and resources: In the USA, participation in screening programs depends largely on the advice of a physician. A long-term relationship based on regular visits is crucial for this, which generally does not exist in the case of socioeconomically worse off US patients.³ In addition, in socioeconomically weaker regions, less well-qualified physicians are predominantly entrusted with screening examinations. This is again immediately noticeable in the case of AAs, which are endoscopically examined much more frequently by physicians who (in contrast to NHWs) are predominantly in the quartile of physicians with the lowest polyps detection rates.⁴
• Other factors that could contribute to health disadvantages of ethnic groups or lower socioeconomic congestion are: the poorer detection rate of, especially advanced adenomas in AAs compared to NHWs. The more frequent - and risk-increasing - localization of such adenomas in the proximal colon in AAs compared to NHWs. Specific mutations in tumors of AAs as well as the tendency to Inflammatory-Associated Microsatellite Alterations (IAMAs), which were associated with more aggressive disease progression. The influence of diet on the adenoma risk and (associated with this) an individual's specific microbiome, which may be increased by a high-fat, low-fiber diet, is also an important factor. Due to availability and costs, such damaging diets are more common in residential areas with poorer socioeconomic conditions than in regions with higher income and living standards. In one study, it was possible to influence the corresponding CRC-related biomarkers favorably in the short and long term by changing to a low-fat, high-fiber diet.⁵

Proposals for intervention

In their work, Carethers and Doubeni suggested that the differences in disease risk and prognosis in the USA should be reduced mainly through community-based measures. Especially at this community level, the existing inequalities in health care could and should be addressed. For too long, they argue, activities in this area have been focused solely on health care facilities such as clinics and hospitals. In the USA, health care facilities are not regularly visited by socio-economically disadvantaged population groups.

Lifestyle changes were also particularly encouraged. However, experience to date has shown that measures to changing eating habits, physical activity and the like are difficult, time-consuming and expensive to implement across the population. Therefore, they could and would generally be generally more difficult to provide to poorer regions. However, information and reminders of screening tests can be sent by e-mail and other media at a low cost and could increase the participation rate by up to 15%.

In general, in addition to improved financial health care provision for local authorities, locally tailored and multimodal programs are the best way to overcome the ethno-socio-economic disparities that are present in CRC incidence.

References:
1. Carethers JM, Doubeni CA, Causes of Socioeconomic Disparities in Colorectal Cancer and Intervention Framework and Strategies, Gastroenterology (2019), doi: https://doi.org/10.1053/j.gastro.2019.10.029
2. Lansdorp-Vogelaar I, et al. Contribution of screening and survival differences to racial disparities in colorectal cancer rates. Cancer Epidemiol Biomarkers Prev 2012; 21:   728-36. https://cebp.aacrjournals.org/content/21/5/728.full-text.pdf
3. Laiyemo AO, et al. Influence of provider discussion and specific recommendation on colorectal cancer screening uptake among U.S. adults. Prev Med 2014; 67: 1-5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4167462/pdf/nihms608003.pdf
4. Fedewa SA, et al. Racial and Ethnic Disparities in Interval Colorectal Cancer Incidence: A Population-Based Cohort Study. Ann Intern Med 2017; 166: 857-866. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5897770/pdf/nihms943176.pdf
5. O’Keefe SJ, et al. Fat, fibre and cancer risk in African Americans and rural Africans. Nat Commun. 2015; 6: 6342. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4415091/pdf/nihms-657331.pdf