Rising Cases of Early-Onset Colorectal Cancer Alarm Experts Worldwide

Published: October 17, 2025, 22:10 EDT

The incidence of colorectal cancer among younger adults is increasing worldwide, prompting concern among oncologists who are calling for stronger public awareness, earlier screening, and more research into potential environmental causes.

Rising Trend Among Younger Adults

Colorectal cancer — once considered a disease of older adults — is now being diagnosed more often in people under the age of 50. Studies reviewed by Harvard Medical School’s Dr. Kimmie Ng show that the rate of early-onset colorectal cancer has been rising by roughly 2% annually since the mid-1990s.

Dr. Ng, a gastrointestinal oncologist at Boston’s Dana-Farber Cancer Institute and founding director of its Young-Onset Colorectal Cancer Center, said the trend is evident across both genders and regions. “It’s shocking to see perfectly healthy young people, with no family history, suddenly facing Stage 4 disease,” she told CNN’s Chasing Life podcast.

Globally, early-onset colorectal cancer is now the leading cause of cancer-related deaths among men under 50. By 2030, experts project it will surpass breast cancer as the top cancer killer in women under 50, according to data cited by Ng.

Understanding the Scale of the Problem

Although the number of younger patients remains relatively small compared with older adults, the increase has drawn attention from researchers and public health officials. Ng emphasized that, in absolute terms, such cases are “still relatively rare,” but the consistent rise suggests a worrying generational shift.

“Younger people face unique challenges,” Ng noted. “Many are raising children, supporting parents, or building their careers. A diagnosis at this stage of life has a massive emotional and social impact.”

Screening Recommendations and Gaps

Screening programs have significantly reduced colorectal cancer rates among older adults. However, those benefits have not extended to younger populations. The U.S. Preventive Services Task Force lowered its recommended screening age from 50 to 45 in 2021 for people at average risk.

Ng said another reduction is unlikely in the near term due to practical and medical factors, including the relatively low incidence rate among very young adults, the cost of large-scale screening, and procedural risks such as bleeding or false positives.

Instead, Ng advocates for a more tailored approach: identifying individuals at higher risk — including those with family histories or genetic predispositions — and encouraging them to undergo earlier screening.

Recognizing Early Warning Signs

Awareness of symptoms is critical to early detection. Among younger patients, the most common sign is blood in the stool, particularly when it is mixed within the stool rather than appearing on tissue or in the bowl.

Other warning signs include unexplained weight loss, prolonged changes in bowel habits such as persistent diarrhea or constipation, thinner stool, abdominal pain, and fatigue that may indicate anemia.

Ng urged young adults to speak openly with healthcare providers about such symptoms, no matter how uncomfortable the conversation may be. “It’s vital to normalize discussions about bowel habits,” she said.

Environmental and Lifestyle Links

Researchers believe environmental and lifestyle factors may be driving the generational increase in colorectal cancer. “Each generation since 1950 faces higher risk,” Ng explained. “Someone born in 1990 now has over four times the risk of developing rectal cancer compared to someone born in 1950.”

The leading hypothesis links this trend to environmental exposures and modern lifestyles. Potential contributors include obesity, sedentary behavior, and diets high in processed meats, refined sugars, and sugary beverages.

However, Ng noted that many young patients do not fit this profile. “Some of them are marathon runners or eat organic diets — yet they’re still diagnosed. This means other environmental factors, such as microplastics or early-life exposure to toxins, could play a role,” she said.

Genetics and Family History

While genetics account for only a small portion of early-onset cancer cases, experts recommend that anyone diagnosed with cancer at a young age undergo genetic testing.

Inherited conditions such as Lynch syndrome or familial adenomatous polyposis can increase the risk of developing colorectal and other cancers. “All young patients should receive familial genetic testing,” Ng said, emphasizing that family medical history remains a vital tool for early prevention.

Individuals with close relatives who have had colorectal cancer may need to begin screening earlier than the general population, which can be lifesaving.

The Psychological and Physical Toll on Young Patients

Younger patients often have the strength to tolerate intensive treatments like chemotherapy, surgery, or radiation. But despite their physical resilience, survival outcomes are not always better than those of older patients.

According to Ng, individuals under 35 tend to have poorer survival rates compared with older patients diagnosed with the same stage of cancer. Emotional strain, disruption to family life, and financial challenges compound the physical burden.

Advocating for Screening and Awareness

Experts continue to stress that screening saves lives. Ng reaffirmed the importance of adhering to recommended screening ages — 45 for average-risk individuals, and earlier for those with family histories.

She encouraged both physicians and patients to break the stigma surrounding gastrointestinal symptoms. “Doctors should routinely ask: ‘Are you seeing blood in your stool? Have you noticed changes in bowel habits?’ These questions could lead to earlier detection,” she said.

Ng also urged public health authorities to renew efforts to reach the national target of screening 80% of the population — a goal that remains unmet.

A Call to Action

The rise in early-onset colorectal cancer underscores the urgent need for awareness, research, and early testing. While the exact causes remain unclear, lifestyle, diet, environmental exposure, and genetics are all under scrutiny.

Health experts agree on one message: pay attention to your body. Recognizing early symptoms, maintaining regular check-ups, and seeking screening at the appropriate age can significantly reduce risk and save lives.