ZIP code vs. genetic code: Understanding CRC disparities in Black Americans
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While hosting the live radio broadcast “Chiefs Rounds” on Sirius XM Doctor Radio, I had the privilege to have Gbenga Ogedegbe, MD, MPH, as my guest. Ogedegbe is a friend and colleague who was recently appointed to run a new endeavor at NYU Langone Health called the Institute for Excellence in Health Equity.
While discussing the horrific fatalities and disparities seen during the COVID 19 Pandemic, Gbenga said something that is well known to health equity researchers: “When it comes to health outcomes and life expectancy, your ZIP code is more important than your genetic code”. This was the case for COVID 19, and since that time, I have been considering if the same holds true for colorectal cancer (CRC) disparities.
We have always known that there are disparities in CRC incidence and mortality and more recently an alarming rise of colorectal cancer in younger adults. For Black Americans, there is about a 20% higher incidence of this disease and about a 40% higher death rate compared with white Americans. Why is that? The short answer is that we don’t really know. Historically, when we see differences in disease incidence based on race or ethnicity, we look for genetic determinants that could explain these disparities. To understand these disparities, we must look beyond the genes.
High CRC Incidence in People of Color
Regarding CRC, there are well known genes, such as the mismatch repair (MMR) genes, that can cause younger and more rapid colon cancer onset within families. However, racial disparities have not been mapped to specific known inherited genetic causes. What about acquired mutational changes? We know that there is a set pattern of chromosomal mutations that can turn a polyp into cancer. In fact, CRC is the template for understanding how normal tissue can transform through a dysplasia-carcinoma pathway over the course of a decade or more.
Unraveling how these known pathways to carcinogenesis relate to young onset CRC and racial disparities is a problem that requires more than understanding the genetics. We must also factor in how the pathways that lead to CRC are affected by the complex and difficult issues around systemic racism and the social determinants of health (SDH).
Only about 25% of CRC is familial, and experts have been trying to figure out what other factors may be responsible for the disparities of higher incidence and mortality in Black Americans. Could chromosomal and epigenetic changes be magnified by social determinants of health such as food supply, housing, diet and nutrition to name a few? How do inadequate transportation, education and access to health care lead to worse outcomes? Are the same causes resulting in the disproportionally higher number of COVID-19 deaths for people of color during this pandemic also at play in CRC?
Eliminate CRC Disparities
As immediate past-president of the ACG during the year in which the pandemic began, I’ve had the unique opportunity to witness how our professional societies addressed disparities in colorectal cancer and the actionable steps they took to better understand and correct them. The ACG has a long history of focusing on colorectal cancer disparities and was the first GI society to recommend dropping the screening age to 45 for Black Americans in their guidelines in 2005 to help offset the younger age of onset and higher incidence and mortality of CRC in Black Americans. Now the American Cancer Society guidelines recommend CRC screening for all Americans at average risk beginning at age 45 and there are new draft United States Preventative Services Task Force recommendations being considered that gives a Grade B for screening all average risk individuals ages 45 to 49 and a Grade A for screening all adults ages 50 to 75.
Public education and advocacy have always been an ACG priority. Telling real stories of families who were tragically affected by colorectal cancer such as Norma Davis-Atkins who lost her husband, Ken, to CRC at age 48, provided Norma and her son Davis the opportunity to advocate for CRC prevention and help others recognize the lifesaving importance of screening. With the deaths of renowned actor Chadwick Boseman at age 43 and Today Show host Craig Melvin’s brother, Rev. Dr. Lawrence Meadows, also at age 43, both young CRC onset of disease and the mortality of Black Americans were made tragically apparent to the American public. The ACG and other organizations continue their efforts to advocate for CRC education on screening, prevention and family history in addition to expanding and supporting research and promoting advocacy.
This past year, the ACG formed a Health Equity Think Tank to work alongside our Diversity, Equity and Inclusion (DEI) committee to address health care disparities by expanding four areas: education, research, policies/practices and pipeline programs/support. The ACG created a “Racism in Medicine” educational series, a “Diversity in GI” symposium and is incorporating a unique Health Equity section within the ACG online Education Universe with DEI representation on each editorial board. In order to generate data to solve questions regarding disparities, the ACG Institute for Clinical Research & Education is developing a new Health Equity Request for Applications to fund research to support new and innovative approaches to combat inequities. To generate data to solve questions regarding disparities, the ACG Institute for Clinical Research & Education is developing a new Health Equity Request for Applications to fund research to support new and innovative approaches to combat inequities. In addition, the Summer Scholars program allows medical students and residents from groups underrepresented in medicine an opportunity to work with ACG faculty mentors, while an annual outreach program called “Prescriptions for Success” provides opportunities and education to high school students. Enhancing this pipeline of research, mentorship and scholarship — and ensuring DEI representation in leadership development — are the first steps toward developing leaders to create a better future that eliminates disparities and broadens discovery and equity.
Ultimately, we must eliminate the CRC disparities we see in Black Americans. We can achieve this goal by expanding our science and studying the impact of the social determinants of health and structural inequities in our society. Only with this broader view can we prevent and eradicate CRC in all Americans equally, regardless of their race, ethnicity or ZIP code.
- References:
- American Cancer Society. Cancer Facts & Figures for African Americans, 2019-2021. Available at: https://www.cancer.org/content/dam/cancer-org/research/cancer-facts-and-statistics/cancer-facts-and-figures-for-african-americans/cancer-facts-and-figures-for-african-americans-2019-2021.pdf. Accessed March 3, 2021.
- Gray DM, et al. Nat Rev Gastroenterol Hepatol. 2020; doi: 10.1038/s41575-020-0330-8.
- For more information:
- Mark B. Pochapin, MD, FACG, is clinical vice chair in the department of medicine and director of the division of gastroenterology and hepatology at NYU Langone Health. He is also the president of the American College of Gastroenterology.
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