A Turning Point in Colon Cancer: Young People Are Finding It Earlier

Early-stage diagnoses for adults aged 45 to 49 jumped, thanks to more screening.

People under age 50 have been appearing increasingly at doctor’s offices in the past few decades, complaining of blood in their stool or bowel or of abdominal trouble or unexplained weight loss. The diagnosis: colorectal cancer. And by that time, it was often too late.

A patient undergoing a colonoscopy.

But that paradigm is finally starting to shift, at least for patients in their 40s.

There has been a jump in people aged 45 to 49 getting screened for colorectal cancer, after recent medical guidelines lowered the screening age for those at average risk. As a result, the disease is being caught sooner, when it is more curable and the treatment is less grueling, according to new research from the American Cancer Society.

The recent screening recommendations designed to catch cases sooner appear to be working.

“It’s thrilling to see this,” said Rebecca Siegel, an epidemiologist at the ACS and an author of the new research. “It means fewer deaths and higher quality of life for people who are diagnosed.”

The findings come in a flurry of research published Monday in the Journal of the American Medical Association. Colorectal cancer screening in the U.S. for adults age 45 to 49 increased by 62% from 2019 to 2023, according to one ACS paper. Early-stage diagnoses then surged, including a 50% relative increase from 2021 to 2022, according to another ACS report.

A trial of more than 20,000 people in the same age bracket was published by a separate group of researchers, showing that testing uptake increases when people are mailed stool tests by default, versus when they are asked if they want a test or a colonoscopy. Screening rates in the trial were low, however, with 19% of people in the trial overall opting to get screened.

“We probably shouldn’t be wasting time asking patients first; we should send them what they need,” said Dr. Folasade May, the trial’s senior author and a gastroenterologist at the University of California, Los Angeles. “We have a long way to go.”

Colorectal cancer rates have been rising for people under age 50 since the 1990s, and the disease is now the leading cause of cancer death among men in that group. Researchers are investigating everything from diet and lifestyle to environmental contaminants, to figure out why colorectal and other cancers are rising in younger adults.

The ACS in 2018 started recommending that people with average risk as young as 45 years old get screened for colorectal cancer, down from the previous start of age 50. The U.S. Preventive Services Task Force followed in 2021; their guidelines carry particular weight among primary-care providers and often lead to health-insurance coverage.

Suddenly, millions of people were newly overdue for screening. For people in that 45-to-49 age bracket, cases jumped, going from about a 1% increase in the incidence rate each year since 2004 to a 12% annual rise from 2019 to 2022, the data show. The rise was driven by diagnoses of early-stage disease.

A post-Covid rebound in people seeking healthcare could contribute to some of the increase, researchers said, but the change in screening guidance is likely the bigger factor. The trend looks similar to what happened among people ages 50 and above in the late 1990s, after screening was first recommended for them, said Caitlin Murphy, a cancer epidemiologist and professor of pediatrics at the University of Chicago, who wasn’t involved in the studies.

It will still take time to see what the impact on deaths looks like for the newly eligible, she said. “Ultimately, the goal of screening is to reduce mortality, and we haven’t seen that quite yet, simply because not enough time has gone by.”

Up-to-date screening via colonoscopy for those aged 45 to 49 rose from around 20% of people in 2019 to about 28% in 2023, according to one of the ACS reports. A colonoscopy is the gold-standard test that also helps doctors remove polyps to actually prevent the cancer from forming. Alternatively, use of tests that look for blood or DNA changes in the stool also increased, rising from 1.3% to 7.1% in that age group.

Screening rates remained mostly stable in all other age groups, the report found.

Screening rates also remained unchanged for people ages 45 to 49 with less than a high-school education or who are uninsured. And they still trail behind those for older adults, who remain at higher risk. Factors including genetics, excess body weight, smoking cigarettes and a diet heavy in red and processed meats also increase a person’s odds of developing the disease.

People in the 45-to-49 age bracket account for nearly half of all colorectal cancers under age 50, ACS said. But that still leaves a lot of people who are at risk and are too young to be screened.

“I have patients in their 20s in my practice that would never fit the guidelines,” said Dr. Michael Cecchini, a medical oncologist and colorectal cancer specialist at Yale Cancer Center. “We need to be thinking about it on our list of possible diagnoses.”

Write to Brianna Abbott at brianna.abbott@wsj.com