Young People’s Gut Bacteria May Be Driving Colorectal Cancer Risk

2 min read

June 5, 2024 – Genetics and diet have been among the top theories for what may be fueling the troubling rise of colorectal cancer in young adults. Now, an early look at genetic data from people with the disease further suggests that the cause is linked to what is happening in the gut.

The findings were presented at the recent American Society of Clinical Oncology conference in Chicago by researchers from Ohio State University. For the analysis, they analyzed genetic data on tumors.

The researchers found signs that a high-fat, low-fiber diet may increase inflammation in the gut that prevents it from naturally suppressing tumors. The cells of young people with colorectal cancer also appeared to have aged more quickly – by 15 years on average – than a person’s actual age. That’s unusual, because older people with colorectal cancer don’t have the same boost in cellular aging.

The rate of colorectal cancer among young people has been rising at an alarming rate, according to a 2023 report from the American Cancer Society. In 2019, 1 in 5 colorectal cancer cases were among people younger than 55. That’s up from 1 in 10 in 1995, which means the rate has doubled in less than 30 years.

2017 analysis estimated that a person’s risk of colorectal cancer increased 12% by eating 3.5 ounces of red or processed meat daily, which is the equivalent of the size of a deck of playing cards. The same study also linked colorectal cancer risk to alcohol intake, citing its ethanol content. Eating a diet high in fiber can reduce a person’s risk.

This latest study aligned with previous findings that link bacteria called fusobacterium to colorectal cancer. It’s not unusual for fusobacterium to be present in a person’s mouth, but it is more likely to be found in the intestines of colorectal cancer patients, compared to healthy people. One study even found that people with colorectal cancer were five times more likely to have fusobacterium in their stool, compared to healthy people.

Colorectal cancer is more common among men than women, “likely reflecting differences in risk factor prevalence, such as excess body weight and processed meat consumption,” the authors of the 2023 American Cancer Society report explained.

People younger than 45 should alert their medical provider if they have constipation, rectal bleeding, or sudden changes in bowel movements, which can be symptoms of colorectal cancer. Screening for colorectal cancer should begin for most people at age 45.