Bacteria in Cancerous Colon Tumors
Sarah Littleton (11 AM Micro) found two articles (here and here) about a possible link between colon cancer and a bacteria. Although this is a promising start, and could lead to a possible vaccine for this very common cancer, a lot of research remains to confirm this preliminary study. Here is Sarah’s summary:
Through different research, scientists have linked stomach, liver, pancreatic and cervical cancers to microbes. Dr. Robert A. Holt, a genomic researcher at the British Colombia Cancer Agency, wondered if bacterial infection could be linked to colon cancer, too. He analyzed RNA in colon tumors from Canadian patients and found that Fusobacterium was in tumors, although this rod-shaped microbe it is not a prominent microorganism in the colon and usually causes gum disease and appendicitis. Dr. Holt says that when microorganisms burrow in tumor cells, it is often what distinguishes a disease-causing microorganism from a harmless microorganism. This doesn’t necessarily mean Fusobacterium is causing the tumor, but it is more prevalent in patients with colon cancer that had spread throughout the body. Fusobacterium was found in the liver of a man with colon cancer and was first reported in a medical journal earlier this year.
Dr. Matthew Meyerson and colleagues at Dana-Farber Cancer Institute in Boston performed similar tests, analyzing DNA instead of RNA in colon tumors from patients in the United States, Vietnam, and Spain. Bacteria cells, viruses, normal cells and cancer cells are all found in tumors and their surrounding environment. Dr. Meyerson wanted to study the relationship between tumors and their microenvironment to see if certain cells promote cancer growth. He and Dr. Holt came up with similar results that were published in the Genomic Research journal; both studies found that Fusobacterium is more abundant in tumors than in healthy colon cells. According to Holt’s study, it is about 415 times more abundant, but he does not have an answer for why. Dr. Meyerson is also unsure why this occurs, and whether Fusobacterium causes cancer or Fusobacterial infection develops because of the cancerous tumor.
One way colon cancer and Fusobacteria could be linked is through inflammation. Fusobacteria and tumors both cause inflammation. Dr. David Relman, a microbe expert at Stanford University, was especially interested that these two studies involving patients from around the world both found similar results. However, he noted that Fusobacteria may be found in tumors simply because they can live in areas of inflammation and they take advantage of the damaged cells. Dr. Meyerson thinks more research needs to be done comparing Fusobacteria in people with healthy colons and people with cancerous tumors.
Both Dr. Holt and Dr. Meyerson plan to study Fusobacteria further. Dr. Holt plans to study polyps, from which colon cancer can develop, and see if the presence of Fusobacteria allows polyps to progress into cancerous tumors. Dr. Meyerson is going to study colon cancer in animals in order to determine if Fusobacteria increase the speed of or possibly cause the progression of cancer.
Fusobacteria have recently been associated with ulcerative colitis and Crohn’s disease, both of which increase the risk of colon cancer. If Fusobacterium is found to cause colon cancer, this could affect screening for colon cancer. There is also hope that a vaccine could be made against colon cancer, which is currently the second most malignant cancer. The vaccine would work similarly to the HPV vaccine used to prevent certain types of cervical cancer. If a vaccine is created, colon cancer could become a disease of the past and thousands of lives could be saved every year.