ontrary to popular belief, the human body is not a sterile environment. We actually have 10 times the amount of bacterial cells in and around our body than we do human cells. These microorganisms (bacteria, fungi) will constantly enter our body, where they will be rapidly detected and neutralized by the immune system. However, under conditions of dysbiosis present during infection and inflammation, environments are created that allow for the establishment of specific microorganisms that wouldn’t otherwise colonize healthy tissues.
The microorganisms that circulate at low levels in our body will sense these niches, home in on them, and start to colonize. There are many conditions in which this is the case, such as the lungs of cystic fibrosis patients, urinary tract infections, or stomach ulcers. This also applies to cancer.
Recently, it was discovered that tumors are also colonized by microorganisms, with different types of tumors having different microbial communities. For instance, the microbial community typically found in liver cancer will be different from the microbial community associated with breast cancer. These bacteria are so sensitive that they will have different signatures even within the same type of cancer. For example, a person with pre cancerous colorectal adenomas will have a different microbial signature than a patient with Stage 2 collorectal cancer. These microbial communities found in our bodies provide signatures that more precisely identify disease.