Thursday, September 09, 2010

what is the role of bacteria in carcinogenesis?

Video - growth hormones and carcinogenesis.

JNCI | Radiation, chemicals, heredity, and viruses have all been linked to cancer. Although bacteria seem to be unlikely contributors to cancer, experts continue to look into their role in carcinogenesis.

In his book, Can Bacteria Cause Cancer?, David Hess, Ph.D., a professor and chair of the Department of Science and Technology Studies at Renesselear Polytechnic Institute, Albany, suggests that bacterial theories of cancer development have been largely overlooked.

Helicobacter pylori was isolated from the human stomach for the first time in 1982. The bacterium can cause stomach ulcers, and those who are infected are more likely to develop stomach cancer. Some health organizations estimate that more than one half of the world is infected with the organism.

The H. pylori–stomach cancer link is one of the few accepted connections between cancer and bacteria. However, Hess argues that bacterial theories related to cancer may not have been given proper consideration.

“I am not a microbiologist and I don’t claim that there is an established relationship, but I can offer an historical perspective on the issue,” Hess said in an interview. “I think it is fair to say that the older attempts to find a single bacterial agent represent a rejected program. However, with emerging linkages between H. pylori and cancer, the research field may be reopening.

“If you look back in the history of science, a number of chronic diseases have been linked to bacteria, so it is not entirely unreasonable to wonder if the long history of clinical findings of bacteria associated with tumor samples or the blood of cancer patients suggests an overlooked pathogenic role.”

Hess added that bacterial advocates were largely ignored because emerging trends favored today’s conventional therapies and because of the extreme nature of some bacterial theories.

“There is good evidence that the bacterial theories and therapies were pushed aside by the emerging trends in support of the chemotherapy and radiation therapy,” said Hess. “There was also evidence that advocates overstated their case by claiming that a single, pleomorphic bacterium caused all cancers.”

However, with the acceptance of H. pylori as a cause of stomach cancer, more doctors and researchers are studying other cancer and bacteria connections.