These are troubling questions that have left researchers across the country perplexed – why are more young people being diagnosed with colorectal cancer, and why do some people have worse outcomes than others? This is a topic of particular interest to Kristin Wallace, Ph.D., and Marvella Ford, Ph.D., MUSC Hollings Cancer Center researchers who study colorectal cancer rates and disparities.
The trend concerns Wallace, who published a study in Frontiers in Oncology in April on genetic markers that could explain differences in diagnoses and outcomes between African Americans and whites. Wallace found that African Americans had proximal adenomas, or non-cancerous tumors, more often than whites and a lower prevalence of rectal adenomas. His group also found that these lesions were more likely to have immunosuppressive signatures, suggesting a compromised immune response to cancer.
In previous work, they found that the disparities were particularly pronounced in younger patients and that a differential immune response might play a role. “There must be an effort to examine why we see such a difference in survival in young African American patients under 50 compared to young Caucasians.”
Colorectal cancer claimed the life of “Black Panther” star and South Carolina native Chadwick Boseman, who died aged 43 after being diagnosed with stage 4 colon cancer. a trend that is becoming all too common, particularly in South Carolina, where many counties were identified as hot spots for early-onset colorectal cancer in a study published in Clinical and Translational Gastroenterology in December.
Ford is interested in behavioral, geographic and socio-economic factors that could lead more young people, especially African Americans, to die of colorectal cancer in South Carolina.
âChadwick Boseman was a young man who was under the recommended age for colorectal cancer screening,â Ford said. âClearly, there is something going on here. The fact that South Carolina is a hot spot, and that he is from South Carolina, makes me want to examine the markers associated with his cancer to determine what may have caused it.
Raymond N. DuBois, MD, Ph.D., director of the Hollings Cancer Center, received a Department of Defense grant to study how dietary fat affects the development of colon cancer. DuBois research is focused on better understanding the disease, its progression, and finding more effective treatment options.
âExactly how dietary fat intake contributes to colorectal cancer remains elusive,â said DuBois. “It is also not known whether dietary fat suppresses a host’s immune response against tumor cells.”
Another area that researchers are studying is the effect of antibiotics on the early onset of colorectal cancer. A Scottish study published in the Annals of Oncology was recently presented at the World Congress on Gastrointestinal Cancer. It found that antibiotic use was associated with an increased risk of colon cancer in older patients and especially younger patients under the age of 50.
The same results were found by researchers at the University of South Carolina in a May 2018 study published in Cancer Medicine. Wallace said long-term antibiotic use can alter the microbiota in the colorectum.
âAntibiotics, given to certain ages over an extended period of time, could change the makeup of microbes in the colon,â Wallace said. âThere are notable differences in microbial infiltrates in the rectum, proximal colon, and distal colon. We depend on this bacteria to behave in a collaborative way. Antibiotics can destroy some of the good bacteria, giving pathogenic bacteria a growth advantage. “
Wallace said the routine use of antibiotics could reset the functioning of the gut and reduce the bacterial diversity present.
Wallace was part of a 2019 study that found that cases of early-onset rectal cancer in whites increased dramatically between 1992 and 2014. Ford argues that while prescribing antibiotics is to blame, it makes sense that more cases are diagnosed in whites than in African Americans.
âWe know that to get an antibiotic you have to see a doctor,â Ford said. âIf you don’t have insurance, you’re less likely to be seen by a doctor. We know there are disparities and issues in access to health care that affect African Americans. “
Minorities at risk
Another area of ââconcern for researchers is why some populations seem to perform worse than others. In the 2019 study, Wallace showed that although rectal cancer in young whites experienced the greatest increase, survival rates for all early-onset colorectal cancers have improved since 1992, except for ‘one group – young African Americans diagnosed with proximal colon cancer.
“The differences can be partially attributed to ancestry and genetics, but lifestyle and behavioral factors, such as obesity, diabetes, smoking and stress, probably play a larger role and can contribute to the early aging that we see in African Americans, âWallace said.
Early aging, or “weathering,” among minorities is a topic of particular interest to Ford. Ford said there are possible relationships between the environment, stressors, negative health behaviors, and physical and mental health disorders. She argued that the daily stressors African Americans face cause them to age faster, leading to earlier diagnoses of illnesses.
âWhen you look at just about any type of disease, including diabetes, cardiovascular disease, and cancer, blacks are diagnosed on average 10 years earlier than whites,â Ford said.
Other factors affecting minority populations are access to care and early detection through screenings such as colonoscopies, which are essential for the outcome of colorectal cancer. Those who live in rural and underserved communities struggle with many of these issues, including insurance coverage. Ford said the National Cancer Institute hopes to address these issues by introducing alternative screening tools that don’t require a person to pay for a colonoscopy in a doctor’s office.
âThere are now fecal tests and kits that people can use at home to detect colon cancer, and then a colonoscopy can be done to confirm the diagnosis,â Ford said. âProviding this dramatically improves access to underserved communities. “
Whatever the cause, clinicians agree that the best results will be for those who contract colorectal cancer at an early stage. The Centers for Disease Control and Prevention recommends regular screening from age 45. However, for people with inflammatory bowel disease, genetic syndromes such as familial adenomatous polyposis or a family history of colorectal cancer, earlier and more frequent screenings may be needed. .
There is no effective therapy for treating advanced colorectal cancer. The five-year survival rate for advanced cases is only 5-15%, compared to over 90% if colorectal cancer is detected in stage 1 or stage 2.
Doctors fear the COVID-19 pandemic could lead to the diagnosis of more advanced colorectal cancers due to a dramatic decrease in the number of screenings taken in 2020. A chart published in the June 18 edition of The Cancer Letter showed that colorectal screening rates drop between March 2020 and April 2020.
Locally, doctors have seen an approximately 55% reduction in screening exams in 2020, according to Brenda Hoffman, MD, and Thomas Curran, MD, both gastrointestinal specialists at Hollings.
âA lot of people feared an increased risk of catching COVID-19 in the medical environment,â Curran said. âOn top of that, people faced a number of economic and social stressors that likely put colorectal cancer screening on the back burner. It can be difficult to focus on your health when you are worried about your loved ones and your livelihood. Yet, as time passes, the potential risks of further delays in screening for colorectal cancer also increase. “
Curran published a study in Cancer Medicine in March detailing disparities in colon cancer and found that there may be a more aggressive phenotype in African American patients that plays a role in worse survival outcomes. He is also concerned about the young people he sees with colorectal cancer. Curran said that one in three new rectal cancer diagnosed affects patients under the age of 55.
“This is why it is extremely important that patients do not delay getting their first screening, which should now be at the age of 45 for medium risk patients, according to the American Cancer Society.”
Screenings become even more important because the majority of colorectal cancers do not cause any symptoms, Curran said. âThere are things patients should immediately bring to the attention of their health care providers, such as blood in the stool, a change in bowel habits, or unintentional weight loss. These type of symptoms often prompt to consider a colonoscopy or other tests to better understand the reason for these symptoms. “
Wallace hopes further research will reveal why more young people are dying from colorectal cancer. Until then, she and other doctors are emphasizing the importance of listening to her body and getting tested.
âColon cancer is almost completely preventable,â Wallace said. “It’s beauty, but also tragedy.”