Colon cancer is killing more young people in the U.S. than any other cancer

Most types of cancer have become less deadly over time in adults younger than age 50 in the U.S. but colon and rectum cancers continue to cost lives at alarming rates, according to a new report from the American Cancer Society. The data show that colorectal cancer has officially become the number one cause of cancer-related deaths among young people.

The report analyzed annual U.S. mortality rates from 1990 to 2023 for the top five deadliest cancers for men and women younger than 50 years old—an age group that researchers have been tracking to understand early-onset cancer risk. Encouragingly, cancer mortality overall in the age group decreased by 44 percent. But rates of colorectal cancer among younger people have been steadily increasing in recent decades, and the disease has leaped from the fifth leading cause of cancer deaths in 1990 to the first in 2023.

“It is an inflection point,” says William Dahut, chief scientific officer at the American Cancer Society. “This is the first time it’s number one for cancer deaths overall for those under the age of 50.”

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Deaths from all other leading cancers, including breast, lung and pancreatic cancers, have declined—which Dahut largely attributes to improvements in therapies. “I think this is another important statement that our investment as a nation in science to develop better treatments is paying off in our young adults,” he says.

In contrast with these positive trends, the colorectal cancer mortality rate has been the only one that has worsened. The findings show it is the leading cause of cancer deaths among men and the second for women after breast cancer—and that it has become the leading cause of cancer deaths for the population overall. Many of the cancers in the study, including colorectal cancer, are typically seen later in life, in people’s 60s and 70s, says Jeff Meyerhardt, a gastrointestinal oncologist and co-director of the Colon and Rectal Cancer Center at Dana-Farber Cancer Institute.

“They’re considered cancers of aging,” he says. “At least in the case of colorectal cancer, the age [of onset] was set for quite a while, until more recently.”

Since the 1990s, colorectal cancer cases in people under age 50 have steadily climbed by about 2 percent annually. And the majority of cases are diagnosed at later stages, when they are more difficult to treat.

“About three fourths, maybe 60 to 70 percent, of the time, people [under age 50] have more advanced disease,” says Andrea Cercek, founder and co-director of the Center for Young Onset Colorectal and Gastrointestinal Cancer at Memorial Sloan Kettering Cancer Center. Despite advances in colorectal cancer treatment, the survival rate for advanced stages of the disease is still low, she says. “This is, unfortunately, what I expected to see,” Cercek says of the new data.

Late diagnosis is one likely factor driving more severe and deadly cases. In the U.S., screening for colorectal cancer—typically using the gold standard, a colonoscopy—is recommended to begin at age 45 for most people without a genetic or family history of the condition. That age recommendation was lowered from 50 just a few years ago in response to the growing incidence rates in younger age groups. Younger individuals with colorectal cancer may not seek medical attention for symptoms such as bleeding in stools, difficult bowel movements, bloating or signs of anemia, all of which can sometimes be confused with other health issues. And doctors may not consider screening such individuals for colorectal cancer because their age puts them at lower risk, Meyerhardt says.

But some researchers think there is more going on beyond delayed diagnosis.

It usually takes years for a colorectal polyp, or small growth, to develop into a cancerous tumor, Dahut says. Scientists are trying to understand when, exactly, tumor growth begins and how rapidly it spreads if the cancer is happening at much younger ages than it did in the past. Cercek says data show the steepest rise in cases has occurred among 20- to 30-year-olds.

“If you think about the typical process for, let’s say, a 22-year-old, the polyp would have had to start, literally, when they were 10,” she says. That’s plausible but difficult to detect without screening people at a very young age, but there could also be difference in the progression of the tumors themselves, Cercek says. “We’re very interested to see if there is something about the process that might be more accelerated, that might be different,” she adds.

Scientists are investigating multiple possible explanations for the trend, including diet, exercise, lifestyle, genetics, environmental factors—even microplastics and antibiotics. But many researchers agree there is no single cause. Narrowing in on credible factors will hopefully lead to more targeted screening for younger people at high risk of the disease, without increasing false positives or unnecessary surgeries or colonoscopies, Meyerhardt says.

Cercek adds that improving therapies so they are less toxic to patients, as well as providing emotional and social support during recovery, will be crucial as the number of younger people who face colorectal cancer continues to rise.

“What’s happening ‘big picture’ is alarming. But it’s super important to acknowledge that survivorship for a young adult with colorectal cancer is life-changing. It’s incredibly difficult and can be incredibly taxing from an emotional, physical and financial standpoint,” she says. “The more that we can diagnose early, the better it will be for our patients.”

And perhaps such improvements in treatment and detection will eventually bring colorectal cancer survival in line with that of other cancers.