By now, we've all probably heard the tragic news. If you haven't, Chadwick Boseman, famously known as the actor of Black Panther, passed away yesterday due to colon cancer. He was diagnosed with stage 3 colon cancer in 2016, and it eventually progressed to stage 4.
With an estimated 17,240 new cases and 7,030 deaths in 2016, colon/colorectal cancer (CRC) still remains the third leading cause of cancer death among African-American men and women. CRC incidence rates were 25% higher in this population compared to Caucasians within the years 2006-2010. The mortality rates were also 50% higher among African Americans, making them the most affected group by colon cancer in the United States (Williams et al., 2016).
But, why are African Americans so disproportionately affected by CRC? The answer lies in genetic and environmental factors, and socioeconomic and cultural barriers.
Genetic and Environmental Factors Contributing to CRC in African Americans
It is estimated that genetic factors contribute to CRC as much as 35%. In 2016, a study was conducted by Case Comprehensive Cancer Center along with Seidman Cancer Center and Case Western Reserve University, who identified new gene mutations unique to colon cancers in African Americans. Tumors found in the African Americans studied contained this mutation, which made the tumors more aggressive and more likely to recur and metastasize, partially explaining why this community is more largely affected than other groups in the United States (Science Daily).
Mutations in the adenomatous polyposis coli (APC) gene are linked to familial adenomatous polyposis. APC mutations ablate a key factor in the regulation of the WNT signaling pathway which regulate cell proliferation, differentiation, polarity, and migration. Also, biallelic mutation of APC is associated with failure to down-regulate beta-catenin, causing over-expansion of the stem cell compartment and the development of an adenomatous polyp (Augustus et al., 2018). It is against this backdrop of information that we understand the genetic influences of CRC in African Americans. And of course, like any other racial or ethnic group in the United States, African Americans are not exempt from hereditary risk factors, which is why this problem is widespread throughout the whole community and not just certain individuals.
Migration studies also strongly support the fact environmental factors greatly influenced this prevalence of CRC in the African-American community. Migration to different environments often leads to different dietary consumptions. Incidence rates of CRC are vastly different for African Americans (60 per 100,000 per year) and South African blacks (5 per 100,000 per year) due to migration which then led to a change in diet. The diet for rural South African blacks is highly enriched in fiber and low in meat and fat, whereas the Western diet is low in fiber and high in meat and fat. A study was conducted in which these two groups switched diets; Pittsburgh African Americans were given the traditional South African black diet, whereas they gave rural South African blacks the Western diet. They then examined changes in the gut microbiome and fecal metabolites. Reciprocal changes were observed in the gut microbiome and the metabolome within 2 weeks of diet switch. From previous studies, we know that the gut microbiome, or the bacteria living in your gut, has a significant impact on not only gut health, but immune system health as well. Diet can change this microbiome, leading to the development of certain diseases that may not be found as often in other populations. The African-American diet is largely high in fat and red meat, foods that drastically change the gut microbiome and therefore impact health and lead to a widespread increase in colon cancers. These diets due to change in environment from migration have also led to obesity in the African-American community, which is a significant risk factor in developing colon cancer. To read more about the gut microbiome, click here and to read more about how diets affect health particularly in African American communities, click here.
Socioeconomic barriers within the primarily low-income African-American community are significant in explaining the increased prevalence of CRC in this community. Without the appropriate income, African American individuals often don't seek access to health resources due to their expensive cost and oftentimes lack of health insurance to cover costs for procedures such as colonoscopies. In LA County, although African Americans only constitute 9% of the population, they make up 26% of the uninsured population (GI Health).
When it's a choice between rent and a colonoscopy, many are going to postpone seeking help from a doctor, especially if they don't see any immediate signs of medical distress, which can be extremely dangerous in a population with an already genetically increased risk of developing CRC. For those who live in rural communities, access to care can be hard to find. Due to all the factors mentioned in this article, doctors actually recommend that African Americans get screened for colon cancers earlier than other populations; the recommended age for the general population is 50 years old, but for African Americans the age is 45. But, without access to proper healthcare due to socioeconomic barriers, many cannot afford to get screened even though they are at a higher risk.
There is also an increased stigma in minority communities, particularly the African-American community, to receive medical attention and get screened for colon cancer through colonoscopy due to trans-generational trauma. Only a few decades ago, African Americans were treated extremely poorly by doctors in clinical experiments. For example, in the Tuskegee Syphilis Crisis, experiments were conducted without the patients' informed consent, and those with the disease were never informed of their health status and never given treatment, even after penicillin became widely available to the public, leading many to die needlessly. Unethical events such as these compounded with institutional racism by the healthcare system have led generations of African Americans to distrust doctors and avoid seeking care. To read more about this event and accounts of racism in medicine, visit this article.
The death of Chadwick Boseman is extremely saddening. He was such an inspiration for many black youth longing to be represented in the entertainment industry. Learning about how many people like him are suffering from this disease due to genetic, environmental, socioeconomic, and cultural influences is also disappointing from a medical standpoint. In order to end these health inequities, we must first be educated about them.