Bowel cancer linked to bacterium19th October 2011
Having high levels of a certain species of stomach bacteria, known as fusobacteria, seems to make people much more likely to get bowel cancer, according to two recent studies from the US and Canada.
The researchers found that tumour cells from bowel cancers had an average of 415 times as many Fusobacteria as ordinary cells.
At first, both sets of researchers were ignorant of the other's results.
The US researchers were also able to make use of a wider variety of tumour samples in forming their conclusion.
Matthew Myerson, a researcher at the Dana-Farber Cancer Institute in Boston and the lead researcher on the US study, said that the finding had opened his eyes to the way colon cancer developed.
He said that he and his colleagues were surprised when they found dense populations of a single bacterium living inside people's bowel tumours.
After doing some more experiments, he and his colleagues found that the bacteria were actually burrowing into the tumour cells.
Both groups of researchers discovered the link between Fusobacteria and bowel cancers by analysing gene sequences of tumour samples.
The Canadian group of researchers identified the presence of Fusobacterium in tumour samples using RNA, while the other group used DNA.
In both cases, the researchers were able to find a significant presence of genes from Fusobacteria, and no other microbe.
In the colon, where microbial human cells vastly outnumber human cells, scientists would expect there to be more diversity.
Furthermore, Fusobacterium has never been particularly well-noted for living in the colon.
Fusobacteria are more usually studied in connection with tooth decay, since they live inside plaque, and skin disorders.
Myerson said that he didn't know what to make of the association, but that the bacteria were definitely hanging around people's tumours.
He said he had no idea whether or not they could cause cancer.
Having a tumour inhabited by bacteria could cause inflammation, which could exacerbate the development of cancer.
David Relman, a microbe expert at Stanford University in the US, who was not involved in either study, said he was struck by the fact that both laboratories found the same result independently.
He said he felt there may be a real association between Fusobacteria and bowel cancer.
If there really is a causal link between Fusobacteria and colon cancer, doctors may one day regularly administer a vaccine.
Other studies have shown that there is a link between Fusobacteria and Crohn's disease, as well as a link between the bacteria and ulcerative colitis.
Relman said that inflammation was known to cause cancer, and that there were micro-organisms that thrived best in inflammatory conditions.
Robert Holt, of Simon Fraser University, lead researcher with the Canadian study, said that he and his colleagues planned to probe early-stage cancer lesions for Fusobacteria infections.
The US-based research team plans to study colon cancer in animals.
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Title: Bowel cancer linked to bacterium
Author: Luisetta Mudie
Article Id: 20095
Date Added: 19th Oct 2011