Colorectal cancer rates are climbing globally, with a particularly alarming rise among young adults under 50. Researchers now believe they may have uncovered a hidden culprit behind the medical mystery. A recent study suggests that early exposure to a toxin produced by harmful strains of E. coli could be a possible driver behind the surge.

In the latest study published in the journal Nature, researchers found that childhood exposure to colibactin, a toxin produced by certain strains of E.coli, damages DNA and these mutations raise the risk of bowel cancer before the age of 50.

In a large-scale genome analysis of 981 colorectal cancer across 11 countries, researchers noted a distinct pattern of DNA mutations caused by colibactin. These specific DNA patterns were over three times more common in patients under 40 compared to those over 70.

Interestingly, these genetic fingerprints were not just seen in young adults, but more often in countries with the highest rates of early-onset colorectal cancer, pointing to a possible link between bacterial exposure and the rising number of young adults affected worldwide.

"These mutation patterns are a kind of historical record in the genome, and they point to early-life exposure to colibactin as a driving force behind early-onset disease," said study senior author Ludmil Alexandrov in a news release.

"If someone acquires one of these driver mutations by the time they're 10 years old, they could be decades ahead of schedule for developing colorectal cancer, getting it at age 40 instead of 60," Alexandrov explained.

While earlier studies including prior research from the same team had linked colibactin to 10 to 15 percent of all colorectal cancer cases, they did not differentiate between younger and older patients.

"When we started this project, we weren't planning to focus on early-onset colorectal cancer. Our original goal was to examine global patterns of colorectal cancer to understand why some countries have much higher rates than others. But as we dug into the data, one of the most interesting and striking findings was how frequently colibactin-related mutations appeared in the early-onset cases," said the first author Marcos Díaz-Gay.

Researchers are now exploring innovative ways to translate these findings into early detection and prevention tools. One promising idea is a stool test designed to detect colibactin-related markers, which could help identify individuals at higher risk for early-onset colorectal cancer. They are also investigating the potential of probiotic therapies aimed at rebalancing the gut microbiome in children to reduce the risk later in life.

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