A specific genetic change in the APC gene is found in most tumors that show a unique pattern of DNA damage caused by colibactin, a toxin produced by certain bacteria, and this genetic change is much more common in tumors with that damage pattern than in those without it.

Colorectal cancers diagnosed before age 50 are three to four times more likely to carry a specific DNA mutation pattern linked to colibactin-producing bacteria than cancers diagnosed after age 50, indicating that exposure to these bacteria earlier in life may be linked to the increase in early-onset colorectal cancer.

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.

DNA damage caused by the bacterial toxin colibactin is found in the earliest genetic changes in colorectal cancer, suggesting that exposure to this toxin happens early in life and helps create the initial mutations that lead to cancer.

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.

Colorectal cancers diagnosed before age 40 are more likely to show specific DNA damage patterns linked to colibactin-producing bacteria than cancers diagnosed after age 70, suggesting that exposure to these bacteria earlier in life may be associated with faster development of tumors in the lower colon and rectum.