Colorectal cancer cases in U.S. children surge sixfold in 20 years

Colorectal cancer diagnoses in children, teenagers and very young adults have risen sixfold in the United States over the past 20 years, according to a 2026 American Cancer Society study, prompting researchers to scramble for answers. The surge is occurring even as overall colorectal cancer rates are falling among older adults who receive routine colonoscopies. The new data, published in Live Science, shows that only a few hundred cases are still recorded each year in people under 21, but the trend is unmistakable and alarming.

The disease has long been seen as an illness of older people, with 55 % of cases diagnosed in those over 65 and just 16 % in anyone under 49. Yet the rise in younger patients mirrors a broader increase in colon and rectal cancers among people under 50. Scientists suspect that lifestyle changes – such as higher consumption of ultra‑processed foods and more sedentary habits – may be driving the shift, but no single cause has been identified. Much of the research focus has turned to the gut microbiome, the community of bacteria that lives in the intestines. Disruptions to this ecosystem can cause inflammation and DNA mutations, but Dr. Christopher Lieu of the University of Colorado warns that the mechanisms are “extraordinarily complex” and likely involve multiple factors.

A study presented by Dr. Erica Arnold of Nationwide Children’s Hospital examined 84 patients diagnosed between 2012 and 2023, finding a median age of 16 and a median symptom‑to‑diagnosis interval of just 12 weeks. Only 20 % of these youths had a close relative with colorectal cancer, suggesting hereditary risk plays a limited role. Alarmingly, 80 % were diagnosed at Stage III or Stage IV, indicating a more aggressive disease course than in older adults. Researchers say the findings underscore the need for better awareness of symptoms in young people and for new screening guidelines that reflect the shifting age profile. Ongoing studies aim to untangle the environmental and biological drivers, with the hope of developing targeted prevention and treatment strategies before the trend continues upward.