The role of microbiome in gastrointestinal cancer

The human microbiome consists of the diverse microorganisms with their equally diverse functional abilities that have evolved over millions of years with humans. This microbiome creates a mutually beneficial symbiotic relationship with their host. Through their varied functions, the human gut microbiota is crucial for preserving health and homeostasis. Any imbalance in this microbial population can lead to an array of diseased states, including cancer especially of the gastrointestinal system. The focus of this chapter is to discuss the mechanisms through which the gut microbiome creates a conducive environment for initiation and progression of cancer. In addition, the effect of microbial products such as short chain fatty acids, bile acids and Trimethylamine N-oxide on the formation of gastrointestinal cancer is also discussed. The various experimental methods and new molecular techniques that have facilitated the characterization and study of microorganisms is also discussed. The developments in microbiome research have shed light on the potential role of gut microbiota for novel biomarker discovery and therapeutic interventions in gastrointestinal cancer, like fecal microbiota transplantation. The prospects of these areas for further exploration are discussed.