Some early-onset colorectal cancers may be caused by exposure to a bacterial toxin within the first 10 years of life, according to a study published April 23 in Nature.
An international research team, led by Ludmil Alexandrov, PhD, from the University of California San Diego, analyzed 981 colorectal cancer genomes from patients across 11 countries for the study.
Here are five things to know from their findings:
- The bacterial toxin colibactin, which is produced by certain strains of Escherichia coli within the colon and rectum, is capable of altering colon cell DNA.
- Researchers found that the specific patterns of DNA mutations left behind by colibactin were 3.3 times more common in cases of early-onset colorectal cancer diagnosed in adults under 40 than in those diagnosed after the age of 70.
The colibactin-related DNA mutations were also prevalent in genomes from Argentina, Brazil, Colombia, Russia and Thailand, which have a high level of early-onset colorectal cancer incidence. - After “molecularly timing” the colibactin-related DNA mutations, researchers found that they arose early in a tumor’s development.
Researchers also found that the mutations account for about 15% of colorectal cancer’s APC driver mutations — the earliest genetic alterations that can drive cancer development.
“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,” Dr. Alexandrov said in an April 23 news release from UC San Diego. - Global incidence of colorectal cancer has doubled every decade for the past 20 years, the release said. In the U.S., the proportion of colon cancer diagnoses among adults younger than 55 increased from 11% in 1995 to 20% in 2019.
- Dr. Alexandrov said “further research is necessary to establish causality,” according to the news release.
Future research will study probiotics to eliminate harmful bacteria strains and develop a test for detecting colibactin-related mutations in stool samples.
Read the full study here.
