Why have colorectal cancers jumped by 500% in kids?

This week, that plea expanded to adolescents, with news that colorectal cancer rates among kids between 10 and 14 and teens from 15 to 19 have risen by 500% and 333% percent, respectively, over two decades. 

“Colorectal cancer is no longer considered just a disease of the elderly population,” lead researcher Dr. Islam Mohamed, an internal medicine resident physician at the University of Missouri-Kansas City, noted in a press release about the findings, which used 22 years of data from the Centers for Disease Control and Prevention. The numbers were shared as part of the runup to Mohamed’s presentation at Digestive Disease Week, a gastroenterology industry gathering beginning May 18. 

In addition to the findings about children and teens, the data showed a 185% rise of colorectal cancers among young adults ages 20 to 24.

Despite alarmingly high percentages, it’s vital to note that actual numbers remain very low: In 2020, only .6 children ages 10 to14 per 100,000 population were diagnosed compared to .1 per 100,000 in 1999. For teens 15 to 19, diagnoses went from .3 to 1.3 per 100,000, and in the young adults group, cases rose from .7 to 2 per 100,000.

“We don’t want hysteria around this—this is not, ‘Go take your kids to a gastroenterologist,” Dr. John Marshall, chief medical consultant with the Colorectal Cancer Alliance, which offers resources including a free screening tool, tells Fortune. “It’s gone from unheard of or very rare to the beginning of a drumbeat.” 

He does see the data more as part of an important, overall shift of these cancers being seen in younger people and evidence of “a trend that did not stop with the 20-year-olds,” he says.

“I’ve been doing this for over 30 years, and at the beginning there was no one under the age of 50,” he shares. “Over the last 20 years we’ve observed this shift to where half of my clinic is now under the age of 50, and part of this is that we do see this very young population emerging, which we hate.” Marshall, who serves as director of the Ruesch Center for the Cure of Gastrointestinal Cancers at Georgetown University, says he’s now treated a patient as young as 15, as well as a 17-year-old who died before her high school graduation. He also counsels pediatric oncologists who are treating adolescents with colon cancer in children’s hospitals. 

Why is this happening?

“We really don’t know,” Marshall says.

In general, known genetic risk factors of the disease include a family history of inflammatory bowel disease or colorectal cancer, while modifiable risk factors include obesity, tobacco use, alcohol consumption, and diets that include low fiber intake, consumption of processed meats, sugar-sweetened beverages, and high fats, as well as, and, possibly, a sedentary lifestyle.

But, Marshall notes of the very young, “It is not unfit, unhealthy people. It is not people with family histories, so we can’t detect any genetic exposure or inheritance.” The leading hypothesis, he adds, is that, as humans, “We have done something to change our microbiome… I tell patients it’s like our own soil inside of us, with the bacteria that live in our GI tracts … which is like a rainforest that needs diversity to be healthy.” Marshall suspects that we’ve done something to fundamentally change our “bacterial mix,” whether from exposure to chemicals and “forever microplastics” or “not playing outside,” and sees a possible connection and “interesting parallel” to the rise in peanut allergies.  

The medical community has historically not examined microbiome balance, as it was not believed to be important, he says, but now “there’s a lot of energy into studying this, because it’s urgent, and we can’t let this go.”

Signs and symptoms—and how to get kids to share the details

Signs and symptoms of colorectal cancers are the same in children and teens as they are in adults, the most common of which are changes in bowel habit, abdominal pain, signs of iron deficiency anemia, and rectal bleeding. “Any bleeding in a kid would be an immediate flare, of course,” Marshall says. 

The trick is how to get a child or teen to report bodily-function details to a parent. 

“I think part of what we need to get to as society is an increased comfort, maybe among family and friends, about it. But that’s a big ask,” he says. 

In the meantime, try sharing information with your teen. “You can’t start with, ‘Did you just have diarrhea?’ It’s too shameful and embarrassing,” Barbara Greenberg, a Connecticut-based psychologist specializing in treatment of adolescents, tells Fortune. “You start by showing them an article or a TikTok, something that talks about the symptoms, and then talk about it. You don’t need to ask about their bodily functions. And if they are bleeding, they’re going to feel relieved.” 

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