Colorectal cancer cases have increased in kids over the last 2 decades. Here's what you need to know.

Research has shown that colorectal cancer cases are increasingly showing up in younger adults. Now, data shows that cases are also rising in kids.

A new 22-year analysis of data from the Centers for Disease Control and Prevention found that there were dramatic increases in colorectal cancers in kids between 1999 and 2020. The researchers found that the rate of colorectal cancers grew 500% in kids ages 10 to 14 during that time, 333% in teens ages 15 to 19 and 185% in young adults ages 20 to 24. The data is being presented at Digestive Disease Week later this month.

It's important to stress that the overall numbers of these cases are low. For example, in 2020, just 0.6 children ages 10 to 14 per 100,000 kids were diagnosed with colorectal cancer, compared to 0.1 per 100,000 in 1999. In teens, the number increased from 0.3 to 1.3 per 100,000, and in young adults, cases increased from 0.7 to 2 per 100,000.

Still, doctors say these increases are worth paying attention to. "These findings are definitely alarming," Dr. Tiago Biachi, a medical oncologist in the Gastrointestinal Oncology Department at Moffitt Cancer Center, tells Yahoo Life. Here's what parents need to know.

Why are these cases increasing?

It's not clear why colorectal cancers in younger people are increasing. However, Biachi says there are a few things to keep in mind.

"It is well known that the process to develop a 'non-inherited' colorectal cancer takes time and the usual interval between a polyp and cancer is five to 10 years," Biachi says. "That means that these children developing colorectal cancer were likely exposed to risk factors since their very young age."

Dr. Jacqueline Casillas, a pediatric hematologist/oncologist and medical director of Jonathan Jaques Children's Cancer Institute at MemorialCare Miller Children's & Women's Hospital Long Beach, tells Yahoo Life that lifestyle factors may play a role, including having obesity, eating diets high in processed foods, living a sedentary lifestyle and taking antibiotics that change a child's gut microbiome. "Is there something [happening] prenatally? We just don't know," she says. "We're going to have to follow this trend."

But Dr. Jeffrey Hyams, a pediatric gastroenterologist at Connecticut Children's Medical Center, tells Yahoo Life that this is still incredibly rare. "I've been practicing medicine for 40 years and I have seen one case of colorectal cancer in a teenager," he says. "I've seen zero cases in people who had no predisposing risk factor for it." (Risk factors for colorectal cancer include having inflammatory bowel disease like ulcerative colitis or Crohn's disease, a family history of colorectal cancer and inherited syndromes like Lynch syndrome and familial adenomatous polyposis, according to the American Cancer Society.)

Dr. Anton Bilchik, a surgical oncologist, chief of medicine and director of the Gastrointestinal and Hepatobiliary Program at Providence Saint John's Cancer Institute in Santa Monica, Calif., also stresses the rarity of this. "One has to interpret these numbers very cautiously," he tells Yahoo Life. "You're talking about a difference of one or two in a million." Bilchik also says that "details on family history and other factors matter."

"This is not a reason to start screening children with colonoscopy, but to discuss what is behind this phenomenon," Biachi says.

What symptoms should parents look out for?

The study found that these were the most common symptoms patients with colorectal cancer experienced:

• Changes in bowel habits with either constipation or diarrhea.

• Abdominal pain.

• Rectal bleeding.

• Signs of iron deficiency anemia.

How to tell symptoms of colorectal cancer from less serious stomach issues

If your child has the symptoms listed above, it doesn't automatically mean they have colorectal cancer, Hyams says — and it's much more likely that the symptoms are caused by something else. Bilchik agrees. "Kids often have gastrointestinal symptoms," he says. "That doesn't mean that every symptom is a sign of a disease."

But Hyams says there are a few things that should push you to get your child evaluated by a doctor. "If any child is having persistent — for more than a month or two — abdominal pain, loose stools with blood, anemia and weight loss, those should be looked at," he says.

Doctors will usually do tests like stool testing, blood work and abdominal X-rays before moving on to a larger procedure like a colonoscopy, Hyams says.

But Casillas recommends being on top of your child's gut health and continuing to push for answers if something seems off. "If your child is not getting better, it should prompt something more in terms of studies," she says.

Bilchik also says the latest study's findings are a good reminder to start healthy habits early. "Start eating healthy young, get plenty of physical activity young," he says.

Still, doctors stress that parents shouldn't panic over these study results. "Colorectal cancer is still incredibly rare in children," Bilchik says.