Scientists have identified E coli bacteria as one of the causes for bowel cancer.
The breakthrough has raised the prospect of a vaccine against the disease, which takes around 16,000 lives a year and is the second most common form of the disease in women after breast cancer, and the third most diagnosed in men, the Daily Mail reported.
Tests on mice and people, carried out in the UK and US, have pointed to the bug being a strong suspect in bowel cancer.
The concern surrounds a version that sticks well to the inside of the lower bowel, or colon, and contains genes that make a toxin which cause the type of damage to DNA usually seen in cancer.
Tests have shown the bug to be much more common in bowel cancer patients than in healthy people.
According to the journal Science, Two-thirds of the 21 samples that were taken from bowel cancer patients contained the bug, compared to just one in five of those that had been taken from healthy people.
Experiments have also shown that mice which had been inoculated with the bug, were at very high odds of developing bowel cancer - as long as the E coli carried the poison-making "pks" genes.
"The research suggests that Ecoli has a much wider involvement in the development of colon cancer than previously thought," the paper quoted Liverpool University's Dr Barry Campbell, a co-author of the study, as saying.
"It is important to build on these findings to understand why this type of bacteria, containing the pks genes, is present in some people and not in others," he said.