Higher Risk for Colorectal Cancer Linked to Bacteria
Based on facts, either observed and verified firsthand by the reporter, or reported and verified from knowledgeable sources.
Newsweek AI is in beta. Translations may contain inaccuracies—please refer to the original content.
Scientists have identified a strong link between childhood exposure to a bacterial toxin called colibactin and the rising incidence of early-onset colorectal cancer, according to an international study published in Nature in April.
The research, led by Professor Ludmil Alexandrov of the University of California, San Diego, analyzed nearly 1,000 colorectal cancer cases from 11 countries, pinpointing distinct DNA mutations in younger patients whose exposure likely occurred before age 10.
Newsweek reached out to Alexandrov via email for comment.
Why It Matters
Colorectal cancer was once considered mostly a disease of older adults, but cases in people under 54 have surged by 11 percent over two decades, now comprising one in five diagnoses in the United States and other high-income countries. Many younger patients lack the typical risk factors—such as family history, obesity, or sedentary lifestyle—prompting new urgency to understand hidden environmental contributors.
The study's findings show how early microbial exposure can leave a "time bomb" of mutations, a report by UC San Diego said, fundamentally changing our understanding of cancer risk and offering potential for early detection or prevention strategies that could save lives as rates keep rising.
A concept image depicting colon cancer.
A concept image depicting colon cancer.
Mohammed Haneefa Nizamudeen/Getty
What To Know
The study found that people under 40 were three to five times more likely to have colibactin-specific genetic changes than older adults with cancer, suggesting childhood bacteria could dramatically accelerate cancer risk.
The research spotlighted colibactin, a genotoxin produced by certain strains of E. coli, a common gut bacterium. Colibactin acts as a so-called "weapon system" for bacteria competing in the intestinal environment and has been shown to damage the DNA of nearby human cells, initiating genetic changes that can progress to cancer, Alexandrov said in a report by NPR.
Not all individuals carrying colibactin-producing bacteria develop cancer. Research shows that around 20 to 30 percent of the population harbors these strains, but their effect depends on factors such as the composition of a person's microbiome, dietary habits, and the presence of other environmental triggers.
While the study identifies a significant association, causality has not been definitively established. Experts said other components, including rates of cesarean births, breastfeeding, antibiotic usage, and the consumption of highly processed foods, could impact the gut microbiome and the risks posed by bacteria like E. coli.
Colibactin-linked cancers are also more common in the U.S. and Western Europe, where a higher frequency of risk factors, from dietary habits heavy in red meat to widespread antibiotic use, could be at play.
Researchers are exploring whether probiotics that displace colibactin-producing strains might lower risk, and work is underway to develop stool tests that detect colibactin-related mutations as an early warning tool.
Experts recommend traditional lifestyle measures such as maintaining a Mediterranean-style diet, regular activity, and not smoking, while urging awareness of early symptoms like abdominal pain, unexplained weight loss, or rectal bleeding.
What People Are Saying
Study author Professor Ludmil Alexandrov said in a report by SciTechDaily: "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."
Marcos Díaz-Gay, a co-author of the study, told UC San Diego Today: "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."
What Happens Next
Researchers plan to further investigate how children become exposed to colibactin-producing bacteria, evaluate the impact of environmental and dietary factors, and develop early detection tests.
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