The recent decrease in the age recommendation for colorectal cancer screening came as no surprise to Chris Lieu, MD, associate director of clinical research at the CU Cancer Center. Like many cancer doctors around the country, Lieu has seen an alarming increase in recent years of cases of colorectal cancer in patients younger than 50.
“Those of us who are in the clinic are shocked by the number of young patients who are perfectly healthy — they aren’t obese, they don’t have underlying diabetes, or high blood pressure — but they’re developing cancer,” he says. “It’s wild.”
What has Lieu particularly concerned is the rise of colorectal cancer cases in patients from underrepresented populations — the fact, for instance, that incidences among younger African Americans are nearly double the number in the young white population.
In April, Lieu and two other researchers published an editorial in Nature Reviews Cancer urging physicians to study the biological causes of early-onset colorectal cancer disparities while keeping in mind how social determinants of health — everything from health care access and systemic inequities to poverty and chronic stress — contribute to the problem.
“There may be multiple things going on,” Lieu says. “We get so focused on the science that sometimes we forget about some of these other environmental and systemic and institutional topics. It’s a good reminder to be a little bit more holistic in the way we look at things.”
At the individual level, while genetics plays a large role in early-onset colorectal cancer, Lieu says, most cases are not caused by hereditary syndromes. More likely culprits, he says, are cellular mutations or even changes in gut bacteria.
“As you move out from there, there are other individual factors that are outside of the body but just as important, if not more so,” he says. “How do race, gender, even insurance coverage, and general health impact the biology and development of early-onset colorectal cancer? How much of what we’re seeing is delayed care because of health care access? What resources are available in a community? Does a community have good primary care for younger individuals?”
Lieu and his co-authors know there is a lot of research going on around the world that addresses different pieces of the problem; in their paper they call for more collaboration and sharing of information in order to inform further studies and possible solutions.
“It’s hard to answer all these questions in one system,” he says. “Even in the past year, there have been a lot of meetings put together over Zoom and efforts to put databases and information together. That’s the first step. Part of this is getting things together, whether it’s laboratory experiments or big databases of patient populations, but part of it is also using the expertise of multiple people to ask answerable questions. To really get that down to why is this happening, and what are the things we can impact on an individual level and also a more macro level.”
Lieu says the timing of the paper is good, given the decrease in the recommended screening age for colorectal cancer. That’s part of the solution, he says, as is simply raising awareness that the disease can strike younger people.
“There has been data published that shows that in older adults, patients may have symptoms for a month before being diagnosed with colorectal cancer; in younger adults, they sometimes have symptoms for more than a year,” he says. “The longer patients wait to establish a diagnosis, the more likely it is they’re going to have an advanced stage at the time of diagnosis."