The incidence of colorectal cancer (CRC) in adults younger than 55 years has been increasing in recent years ― a “dramatic increase” was noted in the United States in 2017, and an increase in incidence has subsequently been seen in many other countries across Europe, as well as Australia, New Zealand, and Canada.
A new study has identified geographic hot spots across the United States, characterized by distinct patterns of early-onset CRC with worse survival among men. The hot spots primarily include counties in the lower Mississippi Delta, west-central Appalachia, and eastern Virginia/North Carolina.
The study was published online on May 15 in the American Journal of Cancer Research.
These data can help to identify some of the risk factors associated with early-onset CRC/mortality, commented lead author Charles Rogers, PhD, MPH, a researcher at the Huntsman Cancer Institute and assistant professor of public health at the University of Utah, Salt Lake City.
“We noted potential explanations for the hot spots,” he told Medscape Medical News. “These include an enduring history of unique challenges, such as inadequate access to care, poor health literacy, and low educational attainment.”
Within hot-spot counties there were also higher rates of poverty, a lack of health insurance, and fewer primary care physicians.
“The disproportionate burden of early-onset colorectal cancer among non-Hispanic black men may result from distinctive stressors coupled with cultural and social expectations that impact screening and care behaviors,” said Rogers. “And while it’s estimated that approximately 14% of all US adults are current smokers, we observed that 24% of the adult population residing in hot-spot counties reported currently smoking and having smoked at least 100 cigarettes in their lifetime.”
Lifestyle and screening
Elements relating to the increase in early-onset CRC include environmental and geographical factors, as well as lifestyle factors, such as diet, obesity, and sedentary behaviors, Rogers commented.
“I think lifestyle factors are huge,” he said. “Consumption of high-fructose corn syrup and charred meat, for example, are worth considering and deserve more attention.”
He emphasized the importance of screening. Most health organizations in the United States recommend that screening start at age 50 years, but the American Cancer Society lowered this to 45 years, and the issue has been hotly debated. Rogers said that adults younger than 50 should be having conversations with their clinicians about screening for CRC. He noted that this is particularly important if they have any symptoms of CRC, have a family history of the disease, or reside in one of the hot spots that were identified in their study.
An expert who was approached for outside comment agreed. Chyke Doubeni, MBBS, MPH, director of the Center for Health Equity and Community Engagement Research at the Mayo Clinic in Rochester, Minnesota, said that anyone with health concerns should discuss preventive measures with their primary care physician.
“Screening for people younger than the age of 50 is currently controversial, as it is not recommended by some guidelines,” he said. “Recommendations for screening are different for people with a family history or certain genetic conditions.”
Such people include those younger than 50 years who have a family history of CRC or advanced adenomas. These patients should share that history with their primary care physician in order to determine when to begin screening and how often to be screened.
“People under the age of 50 who have symptoms such as unexplained rectal bleeding or iron deficiency anemia that may suggest the presence of colorectal cancer should be promptly evaluated for that possibility,” Doubeni added.