Colorectal cancer is now the most common cause of cancer death for people under age 50 in the United States.

Colorectal cancer (cancer of the large intestine or rectum) is now the leading cause of cancer death in people under 50 in the United States, a new study finds.

Colorectal cancer incidence and mortality rates for people under age 50 have increased each year since 2013 and 2004, respectively, according to a study released March 2 by the American Cancer Society (ACS). This increase in early-onset diagnoses is driven by advanced-stage disease. (Colorectal cancer is also called colon cancer.)

“This trend is very serious,” study co-authors Rebecca Siegel, Nikita Sandeep Wagle, and Dr. Ahmedin Jemal told Live Science in a co-authored email. Siegel is senior scientific director of cancer surveillance research at ACS. Sandeep Wagle is the principal investigator of the ACS Cancer Surveillance Study. Jemal is ACS’ senior vice president for surveillance, prevention, and health services research. “Colorectal cancer is the only common cancer [in people] “Mortality rates are increasing for those under 50,” they wrote.

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Incidence is also increasing among adults aged 50 to 64, with the disease being diagnosed at a more advanced stage. This may be associated with a similar increase in mortality in this age group, the authors said in their study.

The trends in people younger than 65 years contrast sharply with the decline in new colorectal cancer incidence and mortality among adults 65 years and older. Because most cases occur in people over 65, this downward trend masks an opposite pattern among younger cohorts, the authors said in their study.

a worrying trend

Colorectal cancer is the second leading cause of cancer death worldwide, primarily affecting people over the age of 65. But colorectal cancer “can no longer be described as an old man’s disease,” Cemal said in a statement. In fact, a 2025 analysis found that in 14 countries, including the United States, Canada, Australia, and the United Kingdom, the number of colorectal cancer cases was increasing among people under age 50, while remaining stable or decreasing among people between the ages of 50 and 74.

However, in the new study, researchers compiled data on the number of new colorectal cancer cases from 1998 to 2022 and the number of colorectal cancer deaths from 1930 to 2023, while focusing on slightly different age cohorts. Data comes from the National Cancer Institute and the Centers for Disease Control and Prevention (CDC).

By narrowing the age range studied, the researchers found that the increase occurred not only in people under 50 but also in people up to 65. “The increase in colorectal cancer is not unique to young people, per se,” the study authors told Live Science.

This phenomenon is called the ‘birth cohort effect’ and means that when an individual is born is more closely related to their risk of disease than when they are diagnosed. This confirms “a real increase in disease due to what we are doing and other exposures,” Siegel said in a statement.

However, it remains unclear what is driving this trend, the authors said in their study.

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“Long-established risk factors for colorectal cancer were identified based on cancer in older adults, who are exposed to different risk factors than recent generations,” Siegel, Sandeep Wagle and Jemal told Live Science. For example, researchers said that across all age groups, nearly 14% of colorectal cancers are attributable to smoking, but people under 50 are less likely to have a history of smoking than older adults.

Since the late 20th century, people have been exposed to new environmental factors that can increase cancer risk, such as microplastics and ultra-processed foods. Studies have also found that colorectal cancer is associated with higher exposure to antibiotics and processed meat.

Colon cancer screening saves lives

The research team estimates that 158,850 new people will be diagnosed with colorectal cancer in 2026. Of these, 47,600 will be between the ages of 50 and 64, and 24,640 will be under the age of 50. More than 55,000 people of all ages are expected to die from the disease this year. Of these, 7% are under 50 years old and 24% are between 50 and 64 years old.

Siegel, Sandeep Wagle and Jemal told Live Science that early diagnosis is important because most people under 50 are diagnosed with advanced stage disease that is difficult to treat.

“Early diagnosis can also be achieved by increasing awareness of colorectal cancer symptoms, such as blood in the stool, abdominal pain, diarrhea, and fatigue, which are often mistaken for other health problems,” the researchers said. “Early attention to symptoms may help move the diagnosis to an earlier, more treatable cancer.”

Screening also allows for early detection and removal of precancerous lesions in the intestines. This accounts for 79% of averted colorectal cancer deaths. Current ACS guidelines state that average-risk individuals (those with no personal or family history of the disease) should begin screening for colorectal cancer at age 45. Medicare covers a variety of screening tests starting at this age, including stool DNA tests and colonoscopies. There are no specific ACS guidelines for high-risk individuals, but earlier and more frequent screening may be necessary.

However, researchers found that only 37% of people aged 45 to 49 are up to date with colorectal cancer screening. Siegel, Sandeep Wagle and Jemal said that half of all deaths under the age of 50 are between the ages of 45 and 49, meaning many colorectal cancer deaths in this population are preventable.