Microbiome control in the prevention and early management of cancer

Abstract

Data accumulated during the past 15-20 years have established that chronic infections may contribute to the development of tumors in humans. Although the impact of certain viruses on human carcinogenesis has been known for some time, the involvement of bacteria in such process was not demonstrated until Helicobacter pylori was confirmed as an etiological agent for stomach cancer. Later, other bacterial species (i.e., Borrelia, Campylobacter, Chlamydia) have been associated with different human malignancies. The availability of antibiotics to these pathogens boosted eradication as the main prevention and therapeutic strategy to manage Bacterially-Promoted cancers. However, more recently, the not surprising emergence of Antibiotic-Resistant cases, along with recent information on the remarkable qualitative and quantitative changes that take place in the normal Tissue/Organ-Specific microbiota at different stages of the carcinogenic process, have suggested the possibility of modifying or restoring the microbiota for cancer prevention strategies and, either alone or in combination with conventional anticancer agents, for therapeutic approaches. This chapter focuses on Helicobacter species (H. pylori in particular) as biological Tumor-Inducing agents, the proposed mechanisms underlying the oncogenic processes which they contribute to initiate, such as gastric cancer, colorectal adenocarcinoma, lung cancer, gastric MALT lymphoma, gastric diffuse Large-B-Cell lymphoma (DLBCL), and biliary tract cancer. Eradication versus microbiota manipulation alternatives are discussed in this context.