Microbial dysbiosis and colon carcinogenesis: could colon cancer be considered a bacteria-related disease?

Abstract

Colorectal cancer (CRC) is posing an increasingly important burden on the health care system, with western countries seeing a growing incidence of the disease. Except for germline DNA mutations which have been attributed to less than 5% of patients, little is known about the main causes of CRC. However, environment factors such as food, lifestyle and medication are now suspected to have a major influence on inducing cancers. Today, exhaustive quantitative and qualitative evaluation of all environmental factors is not possible. Various environment-induced diseases have been characterized based on colon microflora, also called microbiota, analyses. Growing data have shown specific changes in microflora (i.e. dysbiosis) in the stools of patients with colon cancer or those adherent to the colonic mucosa. Thus, it appears that microbiota may be considered a platform offering host and environment interactions for studying CRCs. The hypothesis that colon cancer might be a bacteria-related disease is suggested and perspectives are discussed.

Fusobacterium nucleatum associates with stages of colorectal neoplasia development, colorectal cancer and disease outcome

“…Microbiome sequencing studies have proven very successful in uncovering novel candidate bacterial species in tumour and stool samples from CRC patients [10,18,19]. In particular, two North American studies in 2012…”

Probiotics modify human intestinal mucosa-associated microbiota in patients with colorectal cancer

“…One of the common characteristics of these potential risk factors is that they can cause alterations in the structure of the intestinal flora (5)(6)(7)(8). These alterations (also called dysbiosis) were hypothesized to be closely correlated with the pathogenesis of CRC (9)(10)(11).…”

Permissive/Protective Interplay of Microbiota with T Cell Adaptive Immune Response in Colon Cancer

“…There is a general consensus regarding the contribution of multiple members of colonic bacterial/microbial community to the induction of tumor formation and progression in colon cancer (40)(41)(42). In general, contribution of microbiota to tumorigenesis has been demonstrated in a number of colon cancer animal models in a germ-free environment.…”