Microbiome and Colorectal Cancer in Humans: A Review of Recent Studies

The tumor microenvironment has recently been well-studied in various gastrointestinal cancers, including colorectal cancer (CRC). The gut microbiota, a collection of microorganisms in the human gastrointestinal tract, is one of the microenvironments associated with colon carcinogenesis. It has been challenging to elucidate the mechanisms by which gut microbiota contributes to carcinogenesis and cancer progression due to complex interactions with the host, including its metabolites and immune and inflammatory responses. Various studies described the influence of diet on reported changes in the composition and microbiota of gut bacteria and its association with CRC. In recent years, metagenomic techniques such as shotgun sequencing and genome-wide association studies focused on understanding the role of the microbiota and the metabolome on early CRCs and colon carcinogenesis to determine if there are modifiable or intervenable targets for CRC. In this review, we will attempt to provide an overview of gut microbiota related to CRC, with particular attention to the findings of recent studies.