Colorectal cancer is the second leading cause of cancer death in the United States, but its target population is changing.
While rates have been declining steadily for more than a decade among adults over 65, cases among another population are suddenly exploding.
Now scientists are working to understand why this change is happening – and why these new cases are so aggressive.
You may have noticed that colorectal cancer is on the rise in people under 50.
However, new research reveals that this increase is more dramatic among a younger population within this group: children aged 10 to young adults in their early 20s.
In fact, one study shows that the younger the group, the greater the increase: colorectal cancer (CRC) increased sixfold in children aged 10 to 14 between 1999 and 2020.
The disease more than quadrupled among adolescents aged 15 to 19 and almost doubled among young adults aged 20 to 24 during the same period.
Another study showed that during this period, the incidence of CRC was relatively stable from 1999 to 2012. Then, the incidence among children aged 10 to 14 began to climb at an estimated annual rate of 70.54% between 2012 and 2015 – a rate that represents an increase of almost 400% during those three years.
But the increase in cases is only part of why these colorectal cancer trends are so concerning.
Why colorectal cancer appears differently in younger patients
Experts are concerned not only about the rising rates, but also about how CRC behaves differently when younger people develop the disease.
When cancer is detected in younger patients, the majority of cases are advanced, aggressive cancers: stage 3 or 4, according to new research. And these younger patients are more likely to have worse outcomes: After treatment, their cancer is more likely to come back, another article suggests.
“We feel like this is a little bit of a distinct disease than what we see in older people,” pediatric surgeon Dr. Erica Arnold told Live Science.
Arnold led research on young CRC patients and found that patients were diagnosed quickly after their first symptoms appeared, about 12 weeks.
The results confirm this conclusion, showing that despite treatment, the cancer returned in 37% of patients. By the end of this study, 45% of CRC patients had died from the disease.
“Part of this could be related to diagnostic delays,” Dr. Christopher Lieu, a gastrointestinal oncologist, told Live Science. “But if you want my honest opinion, it suggests that these cancers develop differently.”
What is causing these changing trends
Experts still don’t know what’s behind these changes. But they suspect that lifestyle factors, such as consumption of ultra-processed foods, lack of exercise and obesity, are important factors explaining the increase in CRC in such young populations.
This may play into imbalances in the gut microbiome, which is the subject of “most of the research” aimed at determining the cause, Lieu said. These factors can cause long-term inflammation, which can trigger mutations leading to cancer.
Additionally, there is the question of whether antibiotics disrupt the delicate balance of the gastrointestinal system. Other researchers believe that the increasing ingestion of microplastics could disrupt the lining of the intestinal tract.
“It can be a combination of foods, antibiotic use and environmental exposures,” Lieu said.
What to pay attention to
Although rates are increasing, colorectal cancer remains very rare in people under the age of 20, with one in 200,000 cases each year. Fewer than 100 cases are diagnosed in children in the United States each year.
That said, it’s important to know the signs when younger populations don’t get routine colonoscopies to check for problems, such as those over 45.
There is one symptom that is the strongest predictor of CRC in people under 50: rectal bleeding.
“If they’re 35 and they come in with rectal pain, they probably don’t need a colonoscopy,” said Dr. Sandra Kavalukas, a colorectal surgeon at the University of Louisville School of Medicine. “But if they complain of bleeding, they are 8.5 times more likely to have colorectal cancer.”
In Arnold’s study, the most common symptoms were back and abdominal pain (74%), changes in bowel habits (45.2%), weight loss (43%), and rectal bleeding (38%).
“If someone under the screening age has rectal bleeding, you should seriously consider a colonoscopy,” Kavalukas emphasized.
Gn Health
