Colorectal Cancer on the Rise: Warning Signs and Risk Factors in Young Adults

Colorectal cancer, once primarily viewed as a disease affecting older populations, is increasing at an alarming rate among young adults. Recent data indicates that 1 in 5 colorectal cancer diagnoses now occur in individuals under the age of 55, and the disease has become a leading cause of cancer-related death in young people.

In the United States, colorectal cancer—which includes both colon and rectal cancer—is the third most commonly diagnosed cancer and the second leading cause of cancer-related death for both men and women. The American Cancer Society estimates that approximately 108,860 new cases will be diagnosed in the U.S. In 2026, resulting in about 55,230 deaths.

Trends in Young Adult Diagnoses

The shift toward younger diagnoses is significant. Since the mid-1990s, cases among people under 50 have increased by approximately 50%. While the overall population has seen a slight decline in incidence, the rate of colorectal cancer in people under 50 is rising by nearly 3% per year.

A study published in the Journal of the American Medical Association (JAMA) in 2026 highlighted a stark trend: while overall cancer mortality for people under 50 in the U.S. Decreased by 44% between 1990 and 2023, colorectal cancer mortality increased by 1.1% annually since 2005. This shift moved colorectal cancer from the fifth leading cause of cancer deaths in this age group to the first.

Clinical observations reflect this trend. Surgeons at Yale Medicine report seeing young patients more frequently, noting a case involving a father in his 30s and a patient as young as 18.

Risk Factors and Prevention

Experts estimate that more than half of colorectal cancer cases in the U.S. May be linked to modifiable risk factors. These include:

• Dietary choices
• Physical inactivity
• Alcohol use
• Smoking

A growing body of evidence suggests that lifestyle and diet play a central role in the uptick of cases among Gen X, Millennials, and Gen Z.

Recognizing Warning Signs

Because many young adults believe they are too young for the disease, symptoms may be ignored or misattributed. Medical professionals from Yale Medicine urge individuals as young as 20 to be vigilant about suspicious symptoms.

Key warning signs include:

• Rectal bleeding
• Constipation
• Sudden changes in bowel movements

The danger of misattribution is illustrated by a patient in his 30s who believed his rectal bleeding was caused by hemorrhoids for several months before receiving a colorectal cancer diagnosis.

Screening and Early Detection

Early action and understanding risk factors can significantly impact outcomes. However, some young adults may avoid screening due to the nature of the tests. One patient described receiving a stool sample kit from a healthcare provider but ignoring it because the process didn’t seem sanitary and grossed her out.

The lifetime risk for the general population remains sobering, with approximately 1 in 25 men and 1 in 26 women expected to develop colorectal cancer. Given the rising incidence in younger cohorts, physicians are encouraging those under 45 to discuss any suspicious symptoms with their doctors immediately.