Screening Uptake, Not Biology, Behind Higher Risk of Colon Cancer in Black People

NEW YORK (Reuters Health) – The reported higher risk of colorectal cancer (CRC) in African Americans compared to whites is likely not related to biology but rather to uptake of CRC screening, a U.S. study suggests.

Researchers did a retrospective, cross-sectional study of U.S. veterans aged 40 to 80 years who had diagnostic or screening colonoscopy between 2002 and 2009 at VA Medical Centers.

In the overall study population, Black veterans had a higher risk of CRC. However, in a subgroup of veterans who underwent routine screening, the risk was the same for Black and white veterans, an indication that the difference is not biological.

Older age and race/ethnicity are independently associated with CRC risk overall, lead researcher Dr. Thomas Imperiale, Regenstrief Institute research scientist and professor of gastroenterology and hepatology at Indiana University School of Medicine, in Indianapolis, told Reuters Health by email.

“However, when asymptomatic persons are considered (i.e., who undergo screening), there are no differences in CRC prevalence among Blacks, whites, and Hispanics, and only small, clinically insignificant differences in the prevalence of advanced precancerous polyps,” Dr. Imperiale said.

A population-based, longitudinal study from Delaware supports this contention by showing that eliminating screening disparities between Black and whites equalized age-adjusted CRC incidence and mortality (

The Delaware experience is a “public-health success story and is perhaps the most powerful/convincing evidence supporting non-biological differences in CRC prevalence between Blacks and whites,” Dr. Imperiale told Reuters Health.

Biology aside, it could be that the higher observed prevalence of CRC in Blacks is because they are not getting screened, as suggested by guidelines, or that they respond to symptoms differently, perhaps delaying seeking evaluation for symptoms of CRC longer than whites, Dr. Imperiale said.

“Thus, a message to Blacks (Veterans in particular, but these data are likely generalizable to non-Veterans) is that their ‘higher risk’ of CRC is not a ‘done-deal’ – it is likely not due to biology,” Dr. Imperiale said.

“CRC is as preventable in Blacks as it is in whites. Blacks should have equal access to screening and hopefully, equal uptake – and should get screened for CRC – either with colonoscopy (depending on other risk factors) or non-invasively (with FIT or FIT/DNA tests),” he added.

“Screening is one of the most powerful tools for preventing or detecting colorectal cancer early, when it is curable,” Dr. Imperiale said.

In a news release, Regenstrief Research Scientist Dr. Nicole Keith, who studies health disparities but was not involved in the study, said, “Often, Black patients do not have access to screening or the ability to attend an appointment.”

“Historically,” she added, “this population has also had trust issues with healthcare, all of which could contribute to these disparities. We need to develop a way to make these important tests more accessible to everyone and improve trust in healthcare.”

The study was supported by the Veterans Administration. The authors have no relevant disclosures.

SOURCE: Journal of Clinical Gastroenterology, online May 28, 2021.

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