Colon cancer rates have been rising for decades in younger people, study finds

Colorectal cancer rates have been rising for decades among people too young for routine screening, new research finds.

Routine screening is recommended every 10 years starting at age 45; the new study focused on rates of the disease in children and adults ages 10 to 44, using data from the Centers for Disease Control and Prevention.

Cases of colorectal cancer were on the rise in all age groups, the researchers found.

“It means that there is a trend,” said Dr. Islam Mohamed, an internal medicine resident physician at the University of Missouri-Kansas City who led the research. “We don’t know what to make of it yet, it could be lifestyle factors or genetics, but there is a trend.”

The findings, which have not yet been published in a peer-reviewed journal, will be presented later this month at the Digestive Disease Week conference in Washington, D.C. 

Despite the increases, the overall number of cases in people younger than 40 was still low. In people under age 30, cases remained exceedingly rare.

But with such low rates to begin with, any increase can take on a larger significance.

The study found that colorectal cancer diagnoses in children ages 10 to 14 jumped from 0.1 cases per 100,000 in 1999 to 0.6 per 100,000 in 2020, a 500% increase. Cases among 15- to 19-year-olds jumped by more than 300%, from 0.3 per 100,000 to 1.3 cases per 100,000 people. In people ages 20 to 24, cases rose from 0.7 to 2 per 100,000 people, a 185% rise. 

“When you are starting off with a very rare disease in 15-year-olds and you add a couple cases, you are going to have a huge percentage increase,” said Dr. Folasade May, an associate professor of medicine in the University of California, Los Angeles Vatche and Tamar Manoukian Division of Digestive Diseases. 

The increases were smaller for people over 25, but they also started with higher rates in 1999 than the younger groups. People older than 25 saw a more moderate, but still significant, rise in cases. The age group that was just too young to be routinely screened — those ages 40 to 44 — saw an increase of 45%, from about 15 per 100,000 people to about 21 cases per 100,000 people in 2020.

“We know this disease is age-related, as you get older you are more likely to develop polyps and those polyps are more likely to develop into cancer,” said May. 

May said that although the overall trend is alarming, it’s reassuring to see that the oldest group had the smallest percentage…