In people with unexplained colorectal polyps, nearly one in three tumor samples shows a specific type of DNA damage pattern that is commonly caused by a bacterial toxin called colibactin, suggesting this bacterium may be involved in causing DNA mutations in some cases.

Researchers found that DNA damage patterns linked to a specific bacterial toxin were present in 39% of colorectal tumors from individuals with APC gene variants, compared to 11% in individuals without these tumors. This suggests a statistical relationship between the bacterial toxin and the type of DNA damage observed in these cancers.

In colorectal cancers infected with bacteria that produce colibactin, a specific pattern of DNA damage caused by this toxin accounts for about one-quarter of harmful mutations in the APC gene, which is known to initiate tumor development.

Certain strains of E. coli that produce colibactin are linked to distinct patterns of DNA damage found in colorectal tumors, particularly in younger patients, and these damage patterns are found in a portion of the mutations that drive tumor development.

Certain strains of E. coli that produce a toxin called colibactin are linked to a specific pattern of DNA damage found in colorectal tumors. This DNA damage pattern is more commonly found in tumors from people diagnosed with colorectal cancer before age 55 compared to those diagnosed at age 59 or older.

In patients with unexplained polyps in the colon, those who have a specific DNA damage pattern linked to colibactin are more likely to carry bacteria in their gut that produce colibactin, compared to those without this DNA pattern.