(NEW YORK) — Colorectal cancer was once viewed as being mostly diagnosed among middle-age and older adults, but that’s changing.
Research shows more adults in their 20s, 30s and 40s are being diagnosed with colorectal cancer, with incidence increasing over the last three decades.
Deaths are on the rise too, with a recent study finding colorectal cancer is now the leading cause of cancer-related deaths in men — and second in women, under age 50.
“It’s definitely incredibly concerning that these rates continue to rise and that we really don’t know why this is happening,” Dr. Andrea Cercek, a gastrointestinal medical oncologist at Memorial Sloan Kettering Cancer Center in New York City, told ABC News.
Oncologists told ABC News that it’s important to get the word out about how colorectal cancer is affecting younger adults in an effort to try and reverse the trends.
Colorectal cancer rising among younger adults
According to the American Cancer Society (ACS), incidence of colorectal cancer in adults between ages 20 and 39 has been rising about 2% every year since the mid-1990s.
What’s more, about one in five people currently being diagnosed with colorectal cancer are under age 55, ACS states.
“Two-thirds of the young patients present already as stage three and four, which is a sad fact,” Dr. Y. Nancy You, a professor of surgery in the department of colon & rectal surgery and medical director of the young-onset colorectal cancer program at MD Anderson Cancer Center in Houston, told ABC News.
Research shows it’s not only colorectal cancer cases that are on the rise among younger adults but deaths as well.
A study published earlier this month from ACS in the medical journal JAMA found that as of 2023, colorectal cancer has surpassed all other cancers as the leading cause of cancer deaths among Americans under age 50.
Since 2005, deaths from colon and rectal cancers in those under age 50 have risen by 1.1% every year, the study found.
“Whenever we see rates increasing for cancers in younger individuals, it does lead to concern as to why this is happening and also how these individuals may know that they could start screening at younger ages,” Dr. Veda Giri, a professor of internal medicine (medical oncology) and director of the early onset cancer program at at Yale School of Medicine, told ABC News.
“So, the concern comes up not only about why, but what can we do now based on our available ways of screening, detecting and treating cancers that we can now implement in this space of early onset colorectal cancer,” she added.
Why are cases, deaths related to colorectal cancer rising?
Oncologists told ABC News they’re not sure why there’s an increase in colorectal cancer among younger adults, but research is ongoing.
Giri said some the rise could be tied to a higher consumption of ultra-processed foods and processed meats along with a lower intake of fiber or other food substances.
She said a great deal of research is being focused on the gut microbiome and whether disruptions from external exposures, such as diet or environment, may play a role.
“There’s been some work going on trying to characterize obesity patterns and rise in colorectal cancer,” Giri said. “Obesity might be a proxy for things like sedentary lifestyle, eating of these ultra-processed foods, and we certainly see a spectrum of patients where some with early onset colorectal cancer may have obesity, but they’re also individuals that are not obese.”
Risk factors including smoking and heavy alcohol use and have been linked with a higher likelihood of developing colorectal cancer.
A family history of colorectal cancer or colon polyps can also raise the risk of colorectal cancer as can genetic conditions such as Lynch syndrome.
Additionally, inflammatory bowel diseases, including chronic ulcerative colitis and Crohn’s disease, can lead to long-term colon inflammation and raise the risk of colorectal cancer.
Experts believe that whatever is behind the rise, it’s likely to be caused by multiple factors rather than one factor.
“I don’t think it’s going to be a single smoking gun,” You said. “I think cancer is a complex disease. It’s heterogeneous. What makes a cell turn cancerous is probably a lot of factors.”
How to reverse the trend
In 2021, the U.S. Preventive Services Task Force lowered the recommended age at which people at average risk should start screening from age 50 to age 45.
For those with a family history of colon cancer, doctors say people should start screening at either age 40 or 10 years before the age a family member was diagnosed, whichever comes first.
“If we can identify individuals at risk, then we could screen those individuals earlier,” Cercek said. “The problem is that we’ve lowered already screening age to 45, which captured a lot of the population, but the steepest rise is actually the 20 to 30 year olds.”
Doctors said they hope highlighting the risk younger Americans face will raise awareness and help them pay attention to any symptoms they develop.
The most common symptoms of colorectal cancer include persistent changes in bowel habits, unfinished bowel habits, rectal bleeding or blood in stool, abdominal pain or discomfort, unexplained weight loss and fatigue.
“We definitely don’t want to create like a reign of terror where any little thing will trigger a cancer worry or cancer workup,” You said. “But at the same time, I think there’s room to improve in terms of whenever somebody does present with symptoms to get them to a cancer workup faster than what is happening today.”
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