Colorectal cancer is the 4th most deadly cancer in the world, and over 1 million people are diagnosed with it each year. It has very few genetic indicators and it is rapidly growing in prevalence, thus researchers believe it is very likely associated with environmental causes. An obvious environmental cause would be the microbiome, and researchers from John’s Hopkins helped establish this link with their recent publication in PNAS. In their article they show that biofilm formation in the colon is tightly correlated with colorectal cancer.
The researchers studied a cohort of people that had colorectal cancer along with healthy people as controls. In those people with tumors they studied the microbiome of the tumors themselves along with other, distal parts of their colons. They discovered that the majority of people with tumors, whether benign or malignant, had thick biofilms growing on and even in the tumor. What’s more, is that the researchers noticed that biofilms were forming all along the colon, even in the distal parts. Biofilms were not seen in healthy patients, and in some of the patients with tumors.
Interestingly, the bacteria in the biofilms between different patients did not necessarily correlate, and so it appeared the presence of biofilms, rather than the composition of the biofilm was critical. Moreover, the biofilms studied decreased the gut permeability, leading to ‘leaky guts’, which we have covered on this blog before.
A normal colon has a mucous layer to prevent any bacteria from infiltrating the underlying epithelial cells. It is possible that people with decreased mucosal integrity are at risk for bacteria to invade and form these biofilms which may eventually lead to cancer. In fact, according to this small study, people with biofilm formation in their colon have a 5-fold increase in their likelihood to get colorectal cancer, much higher than any other known indicator. More research on a larger scale still needs to be performed. Still though, biofilm detection could be a useful diagnostic for colorectal cancer, and biofilm management could be a target for drugs or probiotics.