NEW YORK (AP) — The worrisome rise in colorectal cancer deaths in younger adults is concentrated in people with less education, suggesting socioeconomic factors could be driving the escalation, according to a new study.

Celebrity deaths — including Chadwick Boseman in 2020 and James Van Der Beek earlier this year — have highlighted the increase in colorectal cancer deaths among younger adults, but the new paper was called the first to parse which people are most affected by the alarming rise.

The researchers found that over the last 30 years, the rise in colorectal cancer deaths in young adults occurred almost entirely among people without a four-year college degree.

Of course, getting a college degree doesn't protect you from getting colon cancer. Rather, experts say it's a marker for other issues: People without degrees tend to earn less money, have poorer diets, exercise less and get less medical care.

It’s not totally unexpected that the death risk is concentrated in the less advantaged, but the paper published Thursday in JAMA Oncology is the first national study to actually show the connection, said Dr. Paolo Boffetta, a researcher at Stony Brook Cancer Center in New York who wasn’t involved in the work.

American Cancer Society researchers used government data on more than 101,000 younger adults, ages 25 to 49, who died of colorectal cancer from 1994 through 2023.

Overall, the colorectal cancer death rate rose from about 3 per 100,000 in that age group to about 4 per 100,000. But for people who only made it through high school, the rate rose from 4 to 5.2 per 100,000, while the rate for people with at least a bachelor's degrees did not change from 2.7 per 100,000.

Ahmedin Jemal, the study’s first author, said the findings underscore the need for public awareness about colorectal cancer and for younger adults to heed screening recommendations. Symptoms can include blood in stool or rectal bleeding; changes in bowel habits, such as diarrhea, constipation or narrowing of stool that lasts more than a few days; unintended weight loss; and cramps or abdominal pain.

The American Cancer Society estimates that more than 158,000 cases of colorectal cancer will be diagnosed in the U.S. this year. Overall, it’s the nation’s second leading cancer killer, behind lung cancer, and is expected to claim more than 55,000 in 2026.

The number of deaths for adults younger than 50 is around 7% of the total — about 3,900. Earlier this year, cancer society researchers reported that colorectal cancer mortality in Americans under 50 had increased by 1.1% a year since 2005, making it now the deadliest cancer in that age group.

Scientists don't know what's behind that increase. But they note risk factors include obesity, lack of physical activity, a diet high in red or processed meat and low in fruits and vegetables, and a family history of colorectal cancer. The American Cancer Society changed its screening guidelines in 2021, lowering the age U.S. adults should start getting screened from 50 to 45.

Why did the researchers behind Thursday's study look at education level and not other factors?

Death certificates don’t detail how much money a person had, or most other aspects of their life. But they do note how much schooling someone completed. And other research has found that data often aligns with statistics about income, health insurance, physical activity and chronic disease. So education serves as a proxy, but can't speak to other factors, like whether the person had health insurance.

“The focus on education is really (due to) something which was available in the data,” Boffetta observed.

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