Racial disparities and early-onset colorectal cancer: A call to action
Colorectal cancer (CRC) is the second leading cause of cancer death in men and women in the United States. Thanks in large part to increased screening of people over 50 over the past decade, overall rates of CRC have declined in the general population. However, the incidence of CRC among younger people in the United States is increasing at an alarming rate. Over the past 20 years, the rate of CRC has increased by 2.2% per year in people under the age of 50. Hidden in these statistics are the significant disparities in CCR incidence and outcomes that exist for African Americans.
Compared to whites, African Americans have a 20% higher incidence of CRC. They are more likely to develop CRC at a younger age, to be diagnosed later in their disease, and more likely to die from their disease. African Americans have the lowest five-year survival rate for CRC of any racial group in the United States. Absolute rates of early CRC, generally defined as CRC diagnosed before the age of 50 to 55, are higher in African Americans than in whites. The recent deaths of Chadwick Boseman at 43 and Natalie Desselle-Reid at 53 are tragic examples of the disproportionate impact of early CRC on the African American community.
Inequalities contribute to many factors that can increase the risk of early CRC
The reasons for this racial disparity in early CCR are unclear. This is not surprising, given our general lack of understanding of the factors behind the increased incidence of early CRC in all breeds.
Some factors that have been linked to early CRC include obesity, physical inactivity, and unhealthy eating habits. According to data from a National Institutes of Health / AARP survey, each of these risk factors may be more prevalent in African American communities, especially those of lower socioeconomic status. African Americans are also less likely to have access to health care. As a result, they may not be able to seek prompt medical attention for symptoms associated with colorectal polyps or cancer. This, in turn, could delay the detection of tumors, which could be cured by colonoscopic removal or surgery if caught early enough. Finally, for reasons that are not entirely clear, once diagnosed, African Americans are less likely to receive chemotherapy or surgery than white patients.
Underlying these potential explanations are pervasive inequalities based on socioeconomic status and systemic racism.
Biological characteristics associated with disparities
African Americans are also more likely to be diagnosed with CRC that originates in the right colon, rather than the left colon or rectum. As I noted in a previous blog post, right-sided colon cancers can be more difficult to detect and their prognosis is worse than left-sided CRCs.
Recent studies suggest that the differences in epigenome of the right versus left colon in African Americans, compared to the pattern seen in whites, could explain the racial differences in the site of origin of CRCs. (An epigenome is made up of chemical compounds that attach to a person’s DNA and influence their expression.) Some data suggests that there may be variation in the molecular profile of tumors that develop in African Americans. compared to whites, which may indicate that the pathways that trigger or encourage the progression of cancers may differ by race. Differences in the gut microbiome have been increasingly implicated in the increased incidence of early CRC and may also contribute to a higher incidence of CRC in African Americans.
Updated screening guidelines may leave African Americans behind
Until recently, most expert bodies generally did not recommend screening for CRC in people under age 50 at average risk, with only the American College of Gastroenterology and the American Society for Gastrointestinal Endoscopy recommending screening. earlier in African Americans. However, in 2018, the American Cancer Society (ACS) changed its guidelines to recommend starting screening at age 45 for people of all races. In October 2020, the US Task Force on Preventive Services released draft recommendations aligned with ACS guidelines.
These new guidelines are expected to have an impact on reducing the early incidence of CRC. However, significant concerns remain about the persistent disparities between African Americans and whites in accessing and participating in CRC testing. In addition, the rates of early-onset CRC increased sharply in people aged 20 to 45 years; the revised guidelines will not apply to people in this age group.
Improvements in racial inequalities and systemic racism are needed, along with medical advancements, to close the gaps in early CRC
With the growing attention given to early-onset RCCs and the long-standing problem of racial disparities in the incidence and outcomes of RCCs, there will hopefully be significant progress in the years to come for respond to these converging public health priorities. This should include continued research into the causes of early CRC, improving early detection through screening and prevention, and access to effective treatment. However, as the root cause of many CRC disparities lies in socio-economic and racial inequalities, there remains an unmet need for the medical and public health communities to address these broader issues.
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The article Race Disparities and Early-Onset Colorectal Cancer: A Call to Action first appeared on the Harvard Health Blog.
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