Advanced Colorectal Cancer Is Climbing Among Adolescents, Study Warns

Colorectal cancer has long been considered a disease of middle and later life, a diagnosis so strongly associated with older adults that symptoms in teenagers rarely trigger the suspicion that matters most: early detection. New research presented at the American Academy of Pediatrics 2026 National Conference & Exhibition, held October 2-6, 2026, at the San Diego Convention Center, adds to a growing body of evidence that this assumption is no longer safe. The study, titled “Clinical Presentation and Epidemiology of Pediatric and Adolescent Colorectal Carcinoma: A Pediatric Surgical Oncology Research Collaborative Study,” found that rates of advanced-stage colorectal cancer are climbing in young patients and that the disease, when it appears in adolescents, behaves in distinctly aggressive ways.

The retrospective analysis examined the medical files of 84 patients aged 21 years or younger who were diagnosed with colorectal cancer between 2012 and 2023 across 34 institutions participating in the Pediatric Surgical Oncology Research Collaborative. Crucially, the investigators excluded patients with known colorectal cancer predisposition syndromes, including hereditary genetic syndromes and inflammatory bowel disease, before their cancer diagnosis. That exclusion is what makes the findings so striking: these were largely sporadic cases, cancers that arose in young people with no identifiable inherited risk, in a population that current screening guidelines essentially do not cover.

The demographic and tumor characteristics paint a sobering picture. The median age at diagnosis was just 16.5 years, with an interquartile range of 14.0 to 19.0, and 56 percent of the patients were male. Of the 84 cancers identified, 65, or 77.4 percent, were colon adenocarcinomas, while 19, or 22.6 percent, were rectal adenocarcinomas. Among the colon cancers, the most common locations were the sigmoid colon and the ascending colon, each accounting for 27.7 percent of cases, and the cohort included five appendiceal adenocarcinomas, an unusually rare tumor type in any age group.

Perhaps the most consequential finding concerns family history. Only 20.2 percent of the patients, 17 individuals, reported having a first- or second-degree relative with colorectal cancer. That means the overwhelming majority of these young patients had no family signal that might have prompted earlier vigilance. In older populations, family history is one of the key triggers for earlier and more frequent screening, and its absence in most adolescent cases removes one of the few practical warning flags clinicians currently rely on.

The symptom profile at presentation was dominated by complaints that are easily attributed to far more benign causes in teenagers. Back or abdominal pain was the most common symptom, reported by 73.8 percent of patients, followed by changes in bowel habits at 45.2 percent, weight loss at 42.9 percent, and rectal bleeding at 38.1 percent. Each of these can be, and frequently is, explained away in young patients as constipation, dietary issues, stress, sports-related strain, or hemorrhoids. The study quantified the cost of that attribution error: the median duration of symptoms before diagnosis was 12 weeks, and the median time to colonoscopy was 13 weeks, delays measured in months of tumor growth in a disease that often behaves aggressively.

By the time diagnosis was finally made, the disease had frequently already advanced. The majority of patients presented with Stage III disease, 51.0 percent, or Stage IV metastatic disease, 29.0 percent, meaning roughly four in five young patients arrived with locally advanced or metastatic cancer. Study author Erica Arnold, MD, a pediatric surgery research fellow, emphasized the distinct nature of the disease in this population. “Colorectal cancer is, unfortunately, becoming more common in adolescents and young adults and represents a different disease than colorectal cancer diagnosed in older adults,” she said. “When diagnosed, it is often aggressive, presenting with late-stage disease and associated with high rates of disease relapse and mortality.”

The pathological features of the tumors support that characterization. On histologic examination, 33.3 percent of the tumors had signet ring features, 39.3 percent had mucin production, and 41.6 percent were poorly differentiated, all features associated with more aggressive biological behavior and worse prognosis. Treatment data reflected the difficulty of managing such disease: 62 patients, or 73.8 percent, underwent upfront surgical resection, while 4 patients, 4.8 percent, underwent attempted resection that could only achieve ostomy creation because the disease was unresectable. Fifteen patients, 17.9 percent, received neoadjuvant chemotherapy before surgery, and 3 patients, 3.6 percent, received definitive chemoradiation.

Outcomes were grim. Thirty-one patients, 36.9 percent, experienced relapse of their disease at a median of 11 months after treatment, and 96.8 percent of those who relapsed had been diagnosed with stage III or IV disease. Statistical analysis identified clear predictors of relapse: patients whose cancer returned were far more likely to have positive lymph nodes at diagnosis, 90.3 percent versus 50.9 percent, poorly differentiated histology, 64.5 percent versus 28.3 percent, and signet ring features, 61.3 percent versus 17.0 percent. All of the patients who relapsed had received adjuvant chemotherapy, underscoring that current treatment intensification was not enough to prevent recurrence in a substantial fraction of cases. By the end of the study period, 38 patients, 45.2 percent, had died as a result of their colorectal cancer.

The genetic testing results add another layer of scientific interest. Forty-six patients, 54.8 percent, underwent germline testing, and among those tested, 8, or 17.4 percent, carried a mismatch repair mutation, 4, or 8.6 percent, had a TP53 mutation, and 2, or 4.3 percent, had an APC mutation. These findings suggest that even among patients without a known predisposition syndrome at diagnosis, a subset harbor heritable mutations that may only be uncovered after cancer develops, reinforcing the argument for broader genetic evaluation in young-onset colorectal cancer and for cascade testing of relatives when mutations are found.

The study’s authors argue that the findings demand a change in clinical mindset rather than an immediate change in screening policy. Given the increasing incidence of adolescent colorectal cancer, practitioners should include the disease in their differential diagnosis when adolescents present with symptoms such as abdominal pain and rectal bleeding without an alternative explanation, taking unexplained weight loss and rectal bleeding in younger patients seriously. As early-onset adult cancers increasingly appear in younger and younger patients, the researchers note that the logistical coordination between adult and pediatric care teams, and carefully tailored treatment regimens, are paramount. For now, the message to clinicians and families alike is one of heightened vigilance: in a teenager with persistent, unexplained abdominal or back pain, altered bowel habits, weight loss, or rectal bleeding, colorectal cancer may be rare, but the data show it is no longer rare enough to ignore.

Subject of Research: Epidemiology and clinical presentation of sporadic colorectal carcinoma in pediatric and adolescent patients

Article Title: Colorectal cancer on the rise in adolescent patients

Article References: Colorectal cancer on the rise in adolescent patients. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: colorectal cancer, adolescent health, pediatric oncology, early-onset cancer, cancer screening, diagnostic delay, signet ring carcinoma, germline testing, American Academy of Pediatrics, cancer epidemiology, rectal bleeding, abdominal pain