Gastroenterologist Richard Zelner, MD, of Orange Coast Memorial Medical Center in Fountain Valley, Calif., shares insight into a recent study examining a possible relationship between low intestinal bacteria diversity and the development of colon cancer.
A study published in the Journal of the National Cancer Institute, led by author Jiyoung Ahn, PhD, of the New York University School of Medicine, examined fecal samples from 47 colorectal cancer patients and fecal samples from 94 people without colorectal cancer. The samples from colorectal cancer patients exhibited a lower diversity of intestinal bacteria than the samples from healthy subjects. Bacteria responsible for the creation of the fatty acid butyrate were among the reduced population of flora. Butyrate has been previously thought to possibly reduce inflammation and cancer development.
Question: What do these findings mean for the field of gastroenterology?
Dr. Richard Zelner: This study is very preliminary. Short chain fatty acids have loosely been associated with colorectal cancer cell development in the past. The study has found that colorectal cancer patients have less of the bacteria in the colon that produce short chain fatty acids that may be responsible for inhibiting cancer development. This suggests that the lack of these bacteria may be causative.
Q: What does this mean for the future of colorectal cancer treatment?
RZ: This study simply establishes an association between a lack of gut bacteria and colorectal cancer. This does not necessarily mean it is causative. The milieu of the colon can be affected by a number of things. Colon cancer patients may have a lesser number of bacteria, but this could be caused by diet, immunological factors or any number of things.
Change in bacterial flora through probiotics may be potentially preventive for colorectal cancer. However, based on this study it is a huge jump to recommend probiotics as prevention for colorectal cancer. There is no data to support probiotics as an effective preventive measure for colorectal cancer.
Probiotics are inexpensive. However, we must use appropriate scientific method to confirm bowel flora indeed has an impact on colorectal cancer. If this is confirmed we will then need to determine the optimal bowel floral as preventive for colorectal cancer and bowel health.
Q: What is the next step in research to examine a potential link between probiotics and colorectal cancer?
RZ: There are many variables that may affect bacterial flora. It may be difficult to control all of these variables. Further studies will need to control as many of the different variables as possible. Variables such as immune status, nutrition, fat intake, weight, fiber, race, alcohol, general health etc., may play a role in each individual's colon flora. Studies will need to be designed to eliminate variables such as these, which may impact bowel flora and may independently affect the risk of colorectal cancer. If a caustic effect of bowel flora is determined we will then need to determine the optimal bacteria and bowel flora to promote bowel health.
At this point the role of bowel flora effecting colorectal cancer is associative not necessarily causative; it is certainly worthy of further investigation. With a host of genetic and dietary factors that may affect colorectal cancer, this may be another piece of the puzzle.
More Articles on Gastroenterology:
Top 10 Issues in Gastroenterology for 2013
9 Statistics on Digestive Disease Care & Costs in the US
AGA Launches New Guidelines for Crohn's Disease