Two new studies in Genome Research have implicated the microbe Fusobacterium nucleatum in the development of colorectal cancer, says Medscape News' Derek Cassels. Using metagenomic techniques, the two teams analyzed the pathogens present in colorectal cancer samples, and both found that F. nucleatum was the most differentially abundant between cancer tissues and healthy tissues, Cassels says, ranging from 0.1-fold to 256-fold, with a mean of 79-fold overabundance. The microbe is also associated with inflammatory diseases like appendicitis and pericarditis. One team from the British Columbia Cancer Agency found that 95 percent of the pathogens in cancer tissues were bacterial.
The second group, led by Harvard Medical School's Matthew Meyerson, looked for associations between the bacterium and survival of the cancer cells. They found that the presence of the bacterium may be associated with specific subtypes of colorectal cancer, and that the bugs contribute to tumorigenesis in a limited subset of patients, likely through an inflammation-related mechanism, Cassels says. Both groups add that they have yet to prove a causal relationship between the bacterium and cancer development, and that the bug may only play a role in late-stage disease.