Colorectal cancer cases in US children rise sixfold over two decades, study finds

Researchers investigating aggressive forms of the disease in youth, pointing to potential environmental triggers

By LineZotpaper AI staff

Published26 October 2026

Read Time3 min

Illustration: Colorectal cancer cases in US children rise sixfold over two decades, study finds

Colorectal cancer rates among children and teens in the United States have increased dramatically over the past 20 years, with diagnoses in children aged 10 to 14 rising from 1 per million in 1999 to 6 per million in 2020, and for those aged 15 to 19 from 3 per million to 13 per million, according to a new analysis of CDC data. The disease remains rare in young people, but new research suggests it often presents more aggressively in this age group.

The findings, presented at the annual meeting of the American Academy of Pediatrics in October, analyzed 84 patients aged 21 or younger diagnosed with colorectal cancer between 2012 and 2023. The median age at diagnosis was 16, and the median duration of symptoms before diagnosis was just 12 weeks. Only about 20% of patients had a close relative with the disease, indicating that hereditary factors are not the primary driver for most young patients.

Eighty percent of study participants were diagnosed at Stage III or IV, meaning the cancer had already spread locally or to distant organs by the time it was found. By comparison, across all age groups, 60% of colorectal cancer patients are diagnosed at those advanced stages, according to the CDC. One-third of the patients in the study also had cellular markers of particularly aggressive cancer.

Dr. Christopher Lieu, a professor of medical oncology at the University of Colorado Anschutz and medical adviser to the Colorectal Cancer Alliance, said the rise likely stems from environmental factors. “Most of the research has really focused on the gut microbiome,” Lieu told Live Science. He noted that microbiome disruptions may spur inflammation, which can trigger DNA mutations that cause cancer, but added that “it’s going to be extraordinarily more complex than that.”

Potential contributors include ultraprocessed foods, antibiotic exposure in childhood, stress, and reduced exercise. A specific variant of the common gut bacterium E. coli is strongly associated with colorectal cancer, but it does not explain all cases. “It may be a combination of food, antibiotic use and environmental exposures,” Lieu said.

Dr. Erica Arnold, a pediatric surgery research fellow at Nationwide Children’s Hospital who presented the study, said symptoms that warrant attention in young people include back and abdominal pain (reported by 75% of patients), changes in bowel movements (45%), unexplained weight loss (43%), and rectal bleeding (38%). While these symptoms often have more common causes, Arnold stressed that persistent or worsening gastrointestinal issues, especially weight loss or blood in the stool, should prompt a medical checkup. “It’s just important to investigate it to make sure we’re catching colorectal cancer earlier rather than later in these patients,” she said.

Lieu called the disease an “extraordinarily rare event” in children but said the data suggest that these cancers may be developing differently in young people. “If you want my honest opinion, it does suggest that these cancers are developing differently,” he said.

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Analysis

Why This Matters

Colorectal cancer rates are rising in young people even as they decline in older adults, suggesting a shift in risk factors that could affect future generations.
The disease tends to be more aggressive when diagnosed in youth, with most cases found late, underscoring the need for awareness of symptoms among parents and clinicians.
Identifying environmental triggers, such as diet, antibiotic use, and lifestyle, could lead to preventive measures and earlier detection strategies.

Background

Colorectal cancer is primarily a disease of aging, with 55% of cases diagnosed in people over 65. The overall rise in cases among those under 50 has prompted research into why younger populations are increasingly affected. The decline in cases among older adults is largely attributed to routine colonoscopy screening, which removes precancerous polyps. For younger people, no routine screening exists, and symptoms are often mistaken for more common conditions.

Key Perspectives

Dr. Christopher Lieu (professor of medical oncology, University of Colorado Anschutz): Believes environmental factors and microbiome disruptions play a key role, but the causes are likely complex and multifactorial. He notes that young people’s cancers may develop differently from those in older adults. Dr. Erica Arnold (pediatric surgery research fellow, Nationwide Children’s Hospital): Reports that young patients often present with advanced disease and that symptoms like abdominal pain, weight loss, and rectal bleeding should not be dismissed. She emphasizes the need for timely investigation to improve outcomes.

What to Watch

Continued research into the gut microbiome and its role in colorectal cancer development in young people.
Updated incidence data from the CDC to track whether the upward trend accelerates or stabilizes.
Potential revisions to screening guidelines if rates continue to rise, particularly for adolescents and young adults without family history.

Sources

Colorectal cancer cases in kids have risen sixfold over past 2 decades ‪—‬ researchers are racing to understand why · Live Science

Checked

11 claims in this story checked against 1 source: 9 supported.

Show each claim

SupportedColorectal cancer cases in US children rose sixfold over two decades.Latest from Live Science: “Colorectal cancer cases in kids have risen sixfold over past 2 decades”
SupportedRates among 10- to 14-year-olds rose from 1 per million in 1999 to 6 per million in 2020.Latest from Live Science: “In 1999, the diagnosis rate in kids ages 10 to 14 was 1 in a million. By 2020, it had risen to 6 in a million.”
SupportedRates among 15- to 19-year-olds rose from 3 per million in 1999 to 13 per million in 2020.Latest from Live Science: “For teens between 15 and 19, the rate of diagnosis went from 3 in a million to 13 in a million in that same time frame.”
Partly supportedOnly about 20% of patients had a close relative with the disease, indicating hereditary factors are not the primary driver for most young patients.Latest from Live Science: “Only about 20% of the patients had a close relative with colorectal cancer, suggesting that for many of these young people, the disease did not necessarily emerge due to hereditary factors.”
SupportedEighty percent of study participants were diagnosed at Stage III or IV.Latest from Live Science: “Eighty percent of the study participants were diagnosed with Stage III or Stage IV disease”
Partly supportedLieu said the rise likely stems from environmental factors.Latest from Live Science: “There is no definitive reason for this rise, Lieu said. Research on the microbiome has suggested that processed food, antibiotic exposure in childhood, stress, reduced exercise and other lifestyle factors may contribute to this increased risk of colorectal cancer.”
SupportedLieu said, “Most of the research has really focused on the gut microbiome.”Latest from Live Science: ““Most of the research has really focused on the gut microbiome,” the community of bacteria and other microbes that live in the gut, said Dr. Christopher Lieu”
SupportedLieu said microbiome explanations are “going to be extraordinarily more complex than that.”Latest from Live Science: ““It's going to be extraordinarily more complex than that,” he said.”
SupportedLieu said, “It may be a combination of food, antibiotic use and environmental exposures.”Latest from Live Science: ““It may be a combination of food, antibiotic use and environmental exposures,” Lieu suggested.”
SupportedArnold said, “It’s just important to investigate it to make sure we’re catching colorectal cancer earlier rather than later in these patients.”Latest from Live Science: ““It's just important to investigate it to make sure we're catching colorectal cancer earlier rather than later in these patients,” Arnold said.”
SupportedLieu said, “If you want my honest opinion, it does suggest that these cancers are developing differently.”Latest from Live Science: ““Some of that might be related to delays in diagnosis,” Lieu said, “but if you want my honest opinion, it does suggest that these cancers are developing differently.””