Microbiome and cancer

Most compartments and organs of the human body are not sterile, bacterial DNA and RNA can be detected using next generation sequencing techniques. All bacterial DNA in a compartment is called the metagenome, all bacterial transcripts are termed metatranscriptome, while all bacterial species is coined the microbiome. The microbiome transforms in neoplastic diseases that is called the oncobiome. Most tumors are colonized by bacteria that supports tumor growth and development. Microbiome compartments distant to the tumors (as the microbiome of the gastrointestinal tract) can also undergo oncobiotic transformation. The metabolic capacity of the oncobiotic microbiome in the gastrointestinal tract is suppressed and the production of a large set of cytostatic and antimetastatic bacterial metabolites is blunted supporting cancer cells proliferation and metastasis. The microbiome of the gastrointestinal tract has pivotal role in setting the tolerance of the immune system against cancer cells, therefore, has prime importance in tumor immunity. Oncobiosis, by itself, cannot induce tumors, but can support tumor growth and metastasis formation. Bacteria have key role in the success of cytostatic therapy and in setting the side effect profile.