December 7, 2013
Scientists Discover Link Between Gut Microbiota And Colorectal Cancer
redOrbit Staff & Wire Reports - Your Universe Online
Colorectal cancer patients have fewer beneficial gut bacteria and more harmful microbes than those without the disease, researchers from the New York University School of Medicine report in Friday’s edition of the Journal of the National Cancer Institute.
While previous research had suggested that gut microbiota played a role in colorectal cancer (CRC), this study is the first to compare samples from both case and control subjects while also considering for potential confounding factors, the researchers said in a statement. The study is reportedly among the largest epidemiological surveys of human gut bacteria and colorectal cancer conducted to date.
Dr. Jiyoung Ahn of the NYU School of Medicine’s Department of Population Health and the NYU Lagone Medical Center, and colleagues analyzed data and samples from 47 case subjects and 94 control subjects participating in a case-control study. The control subjects were gender and body mass index matches for the case subjects, and DNA was extracted from the fecal samples of all participants.
That DNA was then sequenced to determine the community structure of gut microbes in both case and control subjects. Odds ratios to determine the relationship between both groups of subjects were first adjusted for age, gender, BMI, race, smoking habits and sequencing batch. They were then calculated using logistic regression analysis, and the researchers found that decreased bacterial diversity in the gut was linked to CRC risk.
“The authors highlight several trends in abundance of some key bacteria in the fecal samples they analyzed from case and control subjects that contribute to the decreased diversity associated with CRC risk which they report,” the journal said of the study, which was funded by the National Institutes of Health (NIH).
Specifically, case subjects showed decreased levels of Clostridia, a type of bacteria that helps ferment dietary fiber into a substance that helps prevent inflammation and carcinogenesis. Furthermore, the researchers found increased levels of Fusobacterium and Porphyromonas, both of which have been linked to mouth and gastrointestinal tract inflammation. The findings could lead to new ways to combat the condition.
“Our findings are important because identification of these microbes may open the door for colorectal cancer prevention and treatment,” Dr. Ahn said. “Our next step is to study how diet and lifestyle factors modulate these gut bacteria associated with colorectal cancer. This may lead to ways to prevent this disease.”