New research suggests that exposure to a toxin produced by certain strains of E. coli bacteria may contribute to the global increase in colorectal cancer among people under 50. The study, published in Nature and funded by Cancer Research UK, analyzed DNA from nearly 1,000 colorectal tumors from patients across 11 countries spanning North America, South America, Asia, and Europe, according to an article in The Guardian.
The international research team, led by the University of California, San Diego, found that genetic mutations caused by colibactin, a toxin secreted by some harmful E. coli strains, were more than three times more common in tumors from patients under 40 compared to those over 70. These signature mutations appeared more frequently in countries experiencing higher rates of early-onset colorectal cancer.
According to the researchers, these mutation patterns likely develop when children are exposed to colibactin before age 10. The toxin disrupts DNA in colon cells, potentially increasing the risk of developing bowel cancer before age 50.
Global health records show colorectal cancer rates increasing in younger adults in at least 27 countries, with incidence approximately doubling every decade over the past 20 years. If this trend continues, colorectal cancer could become the leading cause of cancer death in that age group by 2030.
Professor Ludmil Alexandrov from the University of California, San Diego, suggested that early-life infection may increase future colorectal cancer risk. In the US and UK, approximately 30-40% of children have colibactin-producing E. coli in their intestines.
One theory proposes that these harmful E. coli strains evolved an advantage in the gut by producing colibactin. While the toxin damages human DNA, it may help the bacteria outcompete neighboring microbes in what researchers describe as “microbial chemical warfare.”
The study doesn’t conclusively prove that colibactin drives early-onset colorectal cancer. If harmful E. coli strains are involved, questions remain about how they emerged, how children are exposed, and whether interventions like probiotics might replace these problematic microbes.
Cancer Research UK notes that over half of bowel cancers are preventable, with risk factors including insufficient fiber intake (25%), processed meat consumption (13%), obesity (11%), alcohol use (6%), and physical inactivity (5%).
Dr. David Scott, Cancer Research UK’s director of Cancer Grand Challenges, acknowledged that while this study provides important insights into early-onset cancers, more research is needed to establish a definitive link between colibactin and increased early-onset colorectal cancer risk. Other research teams are investigating the microbiome and environmental factors to better understand the global rise in these cancers.
Commenting on this article, the nation’s leading E. coli lawyer said, “E. coli is a particularly problematic pathogen. Most people recover but, in some situations, the infection can develop into hemolytic uremic syndrome, an extremely dangerous condition that can create severe problems if not treated.”
