A specific pattern of DNA damage caused by a bacterial toxin can be identified in tumor samples using a targeted DNA sequencing test called MSK-IMPACT, without needing to sequence the entire genome.

Colorectal cancers with a specific DNA damage pattern linked to colibactin-producing bacteria show more widespread changes in their genome compared to cancers without this pattern.

The presence of certain bacterial genes in stool samples does not reliably indicate how much DNA damage is present in colon tumors, meaning the amount of these bacteria alone cannot be used to predict tumor damage levels in individuals.

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.

When human colon tissue grown in the lab is exposed to a specific type of E. coli that produces colibactin for three months, it develops a unique pattern of DNA damage that matches the pattern seen in human colorectal cancers.

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.