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Bacteria film location, consistency differs in healthy, cancerous colons
As colon cancer rates increase in the U.S., researchers are looking to gut microbiota to find early predictors, such as bacterial biofilms found on the colon mucosa surface, according to a presentation at the NIH’s conference, “The Human Microbiome: Emerging Themes at the Horizon of the 21st Century.” In a recent study, signs pointed to increased and localized biofilm development in patients with colon cancer.
“By defining the microbial drivers of colon carcinogenesis, we can design new approaches to the prevention of human colon cancer,” Cynthia L. Sears, MD, from the Johns Hopkins School of Medicine, said in her presentation. “When diagnosed early, colorectal cancer — which is a leading cause of cancer death in men and women — is a completely preventable disease.”
Sears and colleagues conducted two studies, one at Johns Hopkins and one in Malaysia, in which they gathered samples from the surface of tumor samples and from normal colon mucosa as far from the tumor as they could gather during resection. As a comparison, the researchers also gathered random biopsies from both the left and right of the colon from patients who underwent colonoscopy.
Biofilms were defined as bacteria in the mucus layer at a very high density and reaching at least 200 microns along the length of the colon.
In the patients with colon cancer, cancer and normal tissue taken as pairs were approximately 94% concordant for biofilms. In the patients who underwent colonoscopy, about 15% had similar polymicrobial biofilms on top of their epithelial cells, but the researchers found they were not typically as thick as those on cancerous tissues. Additionally, while biofilms were distributed near equally throughout the colon of healthy patients, there was a higher prevalence in the right side in patients with colon cancer.
With the support of the National Cancer Institute, the researchers have initiated a longitudinal colonoscopy study to define the epidemiology and significance of biofilms as they occur in healthy patients and those with colon cancer. The researchers have enrolled 600 participants so far and expect 2,000 patients in total with over 50,000 samples.
Their goal is to further define the microbiome’s involvement in human disease and any potential carcinogenic causality. Specifically, in colon tumors, the researchers seek to find if the formation of biofilms or the presence of any specific microbe or community consistently proceeds development of colon polyposis in humans.
“This is of course a challenge, because we know that the time from the clonal expansion of that cancer cell in the colon to the visualization of a polyp is at least 10 years and maybe up to 40 years,” Sears concluded. “So, these chronic, slow diseases — many of which are discussed here — pose a particular challenge in trying to link the microbiome to disease.” – by Talitha Bennett
Reference: Sears CL. Biofilms as a risk factor for human colon cancer. Presented at: The human microbiome: Emerging themes at the horizon of the 21st century; Aug. 16-18, 2017; Bethesda, MD.
Disclosure: Healio.com/Hepatology was unable to determine relevant financial disclosures at the time of publication.