A new American Cancer Society (ACS) analysis published in CA: A Cancer Journal for Clinicians shows a worrying shift: a growing share of colorectal cancer cases are occurring in younger adults. From 2013 to 2022 overall U.S. colorectal cancer incidence fell by nearly 1% per year, but that decline was driven by a 2.5% annual drop in people 65 and older. By contrast, rates rose 0.4% per year in adults 50–64 and about 3% per year in those 20–49.
The ACS projects that about 45% of colorectal cancer diagnoses this year will be in people younger than 65, up from 27% in 1995. It also estimates that roughly one-third of the roughly 55,000 expected colorectal cancer deaths this year will be in people under 65. Rectal cancers have become more common within the mix, making up about 32% of colorectal cases now versus 27% two decades ago.
Why the jump in younger people?
Colorectal cancer is the third most commonly diagnosed cancer in both men and women in the U.S. and the second-leading cause of cancer death overall. The ACS estimates about 158,850 new cases in 2026 (roughly 108,860 colon and 49,990 rectal). More than half of cases are linked to modifiable risks: excess weight and obesity, physical inactivity, diets high in red and processed meats and low in fiber, heavy alcohol use, and tobacco.
Clinicians treating colorectal cancer say the rise in early-onset disease is real and troubling. Experts point to several likely contributors:
– Diet and lifestyle: greater consumption of ultra-processed foods, sugars and red meat combined with lower fiber intake and less physical activity may increase risk.
– Environmental exposures: newer, cumulative exposures over recent decades — for example microplastics and other pollutants — could play a role, though research is ongoing.
– Microbial factors: certain gut bacteria can produce toxins that damage DNA and may promote tumor development; investigators are exploring how the microbiome influences risk.
– Changes in early-life exposures: differences across generations in diet, environment and antibiotic use may matter.
ACS researchers and oncologists stress that these factors are not yet fully proven drivers but deserve intensified study. The pattern of rising cases in younger age groups suggests that exposures that began or accelerated in the late 20th century may be contributing.
High-profile cases and rising awareness
Several well-known early-onset cases have focused public attention on the issue. Research presented at Digestive Disease Week found that colorectal cancer cases among U.S. teens more than tripled from 1999 to 2020. Other studies have linked symptoms such as rectal bleeding to early-onset colorectal cancer in adults under 50, highlighting the importance of recognizing warning signs.
Screening, symptoms, and prevention
Because early-onset colorectal cancer has increased, the U.S. Preventive Services Task Force now recommends routine screening begin at age 45 for most adults. Screening methods include colonoscopy and at-home stool-based tests. Clinicians emphasize that screening remains the most effective tool for preventing colorectal cancer and detecting it early.
Young adults should watch for warning symptoms: rectal bleeding, persistent changes in bowel habits, abdominal pain or cramping, unexplained weight loss, and signs of anemia such as fatigue or weakness. Awareness is rising among people in their late 40s and 50s, but remains lower among those under 45.
Practical steps to reduce risk and act promptly
– Follow screening recommendations, beginning at age 45 unless your clinician advises otherwise.
– Know your family history: discuss earlier or more frequent screening if colorectal cancer runs in your family.
– Adopt healthy habits: maintain a healthy weight, stay physically active, avoid smoking, limit alcohol, eat plenty of fruits, vegetables and fiber, and reduce ultra-processed foods, added sugars and red or processed meats.
– Seek medical attention quickly for warning symptoms like rectal bleeding or major bowel changes.
What researchers and clinicians want next
Experts call for greater vigilance: expand public awareness, ensure timely screening and care, and accelerate research into environmental, microbial and other causes of early-onset colorectal cancer. Identifying drivers and effective prevention strategies will be essential to reversing the upward trend among younger adults.
