On the Search to Elucidate the Role of the Microbiota in the Genesis of Cancer: The Cases of Gastrointestinal and Cervical Cancer

The microbiota that inhabits the human body plays an important role in health and disease, by their fundamental role in food digestion, training of the immune system or protection against pathogen colonization. However, when the equilibrium with its host is altered, some diseases like cancer might be promoted. In this review we describe the information collected in recent studies between the microbiota and its association with cancer. We conducted the review of the relation of microbiome and cancer etiology focusing on the gastrointestinal and cervical cancer. The MEDLINE database was used for the search. The gastrointestinal tract harbours a diverse and site specific microbiota, and several studies have demonstrated that perturbation of these microbial communities might be associated with different types of cancer. In particular, alteration of the colorectal, gastric and oesophageal microbiota have been reported associated with cancer development. Likewise, cervical microbiome studies suggest that some members of the cervical microbiota are possible modifiers of the cytokine profile of the cervical microenvironment during the development of cervical lesions and cervical cancer. Larger prospective studies are needed to examine whether microbiome dysbiosis could cause cancer, and to evaluate the utility of microbiome profiles as biomarkers for prevention and early diagnosis. This is an important area of research if we consider that microbiota may be a modifiable factor by the use of pre- and probiotics, in order to prevent cancer evolution or even to potentiate cancer treatment.