Colorectal Cancer in Teens and Young Adults Is Often Found Late, and It May Be a Different Disease

Keypoints:

• A multicenter study tracked 84 patients aged 21 or younger diagnosed between 2012 and 2023
• About 80% were diagnosed at Stage III or IV
• 36.9% relapsed at a median of 11 months, and 45.2% died of the cancer during follow-up
• Most had no known family history of colorectal cancer
• Symptoms to watch include abdominal or back pain, bowel changes, weight loss and rectal bleeding

New research adds to growing concern about colorectal cancer in young people. The study followed 84 patients aged 21 or younger at 34 medical centers in the Pediatric Surgical Oncology Research Collaborative. Diagnoses were made between 2012 and 2023. About 80% already had Stage III or IV disease, which means the cancer had spread.

Delay was common. Many patients were diagnosed three or more months after symptoms began. The most frequent symptoms were back or abdominal pain, a change in bowel habits, weight loss and rectal bleeding. Because colorectal cancer is so unexpected at this age, doctors often look for other causes first.

Outcomes were serious. More than a third of patients, 36.9%, relapsed at a median of 11 months. A total of 45.2% died of colorectal cancer during the study period. One of the authors, Dr. Arnold, said cancer diagnosed through age 21 appears to be a distinct disease from the one seen in older adults.

The absolute risk remains small. Colorectal cancer in people under 20 is about one in a million, with fewer than 100 cases a year in the United States. Most patients in the study had no known family history. About half had genetic testing, which found a handful of mutations that can raise cancer risk.

The bigger trend is clear. A person born in the 1990s is four times more likely to be diagnosed before age 50 than someone born in the 1960s. Obesity, sedentary behavior, sugar-sweetened drinks and ultraprocessed foods have all been linked to early-onset cases. Researchers say the causes are not settled.

The authors urge doctors to consider colorectal cancer when adolescents have these symptoms and no other explanation. Routine screening for average-risk adults usually begins at 45, so younger patients depend on symptoms being taken seriously.