Overall, cancer death rates in people younger than 50 have dropped by 44% since 1990. Only colorectal cancer deaths have increased.

It`s unclear why colorectal cancer rates are increasing among young people. NoonVirachada / Getty Images/iStockphoto

Colorectal cancer is now the leading cause of cancer deaths among people younger than 50 in the United States, according to a study published Thursday in the Journal of the American Medical Association.

Colorectal cancer death rates in that age group climbed by 1% every year since 2005, in stark contrast with the larger trend: Overall, cancer death rates in people younger than 50 have dropped by 44% since 1990. And of the five most common causes of cancer-related death in people younger than 50, colorectal cancer deaths were the only one to increase.

"It is absolutely an outlier," said Rebecca Siegel, senior scientific director of surveillance research at the American Cancer Society, who led the study.

While most colorectal cancer cases still occur in people older than 50, the number of people being diagnosed with the disease in their 20s, 30s or 40s has been climbing dramatically in the last few decades. In light of the trend, researchers previously projected that colorectal cancer deaths would take the No. 1 spot for cancer deaths in people under 50 by 2030.

It claimed that spot seven years sooner than expected, in 2023, the new study found.

Siegel and her colleagues analyzed National Cancer Institute data from nearly 1.3 million people younger than 50 who died of cancer from 1990 through 2023. In 1990, colorectal cancer was the fifth-leading cause of cancer deaths in all people younger than 50. By 2023, it was the first.

In contrast, deaths from the four other leading causes of cancer deaths declined. Lung cancer deaths in the group fell from first to fourth overall, declining by nearly 6% annually from 2014 to 2023. Deaths from leukemia dropped from third in 1990 to fifth in 2023 and declined by nearly 2.5% every year from 2014 to 2023.

Breast cancer remained the second-leading cause of cancer death overall and the leading cause in women, but deaths declined by 1.4% annually from 2014 to 2023.

The declines in other cancer-related deaths don`t fully explain why colorectal cancer deaths are now the leading cause of cancer deaths in younger men and women, said Dr. Andrew Chan, chief of the clinical and translational epidemiology unit at Massachusetts General Brigham in Boston.

"We`ve had some successes in reducing deaths from other types of cancer, which only magnifies the increase in colorectal cancer death, but the rapid rise in colorectal cancer deaths in people younger than 50 is still quite remarkable," said Chan, who wasn`t involved in the study.

The increases "really outpace the declines in death rates from other types of cancer," he added.

Although cases of colorectal cancer are rising, that alone also can`t explain why the death rates from the disease are increasing among young people, Chan said. Indeed, the study found that while cases of breast cancer and leukemia increased, death rates decreased.

While the overall decline in cancer-related deaths is welcome news, the findings starkly highlight the worrying rise in colorectal cancer deaths among young people, said Dr. Folasade May, an associate professor of medicine in the UCLA Vatche and Tamar Manoukian Division of Digestive Diseases.

"It`s a good-news, bad-news story, and for a colorectal cancer doctor, it`s a horror story," said May, who wasn`t involved with the study.

It`s unclear why colorectal cancer rates are increasing among young people. About 20% of cases of colorectal cancer are diagnosed in people who are 54 or younger, double the rate in 1995, according to a 2025 American Cancer Society report.

The trend is clear, but the cause is still poorly understood, said Siegel, the study author.

Research suggests that rising rates of obesity and declining physical activity, changes in the gut microbiome and diets high in ultraprocessed foods, which have become more common since the 1980s, could be to blame.

But "it`s thought that other factors are at play and that these are not the sole reason for the increase," Siegel said.

It`s crucial that young people understand that their risk for colorectal cancer has increased and get screened, especially if they have symptoms, such as blood in their stool or stomach cramping, Siegel said. The U.S. Preventive Services Task Force recommends universal screening starting at age 45 and earlier for people who are high-risk.

"Half of the people diagnosed before age 50 are aged 45 to 49, so they are screening-eligible," Siegel said.