Emerging role of human microbiome in cancer development and response to therapy: special focus on intestinal microflora

In recent years, there has been a greater emphasis on the impact of microbial populations inhabiting the gastrointestinal tract on human health and disease. According to the involvement of microbiota in modulating physiological processes (such as immune system development, vitamins synthesis, pathogen displacement, and nutrient uptake), any alteration in its composition and diversity (i.e., dysbiosis) has been linked to a variety of pathologies, including cancer. In this bidirectional relationship, colonization with various bacterial species is correlated with a reduced or elevated risk of certain cancers. Notably, the gut microflora could potentially play a direct or indirect role in tumor initiation and progression by inducing chronic inflammation and producing toxins and metabolites. Therefore, identifying the bacterial species involved and their mechanism of action could be beneficial in preventing the onset of tumors or controlling their advancement. Likewise, the microbial community affects anti-cancer approaches' therapeutic potential and adverse effects (such as immunotherapy and chemotherapy). Hence, their efficiency should be evaluated in the context of the microbiome, underlining the importance of personalized medicine. In this review, we summarized the evidence revealing the microbiota's involvement in cancer and its mechanism. We also delineated how microbiota could predict colon carcinoma development or response to current treatments to improve clinical outcomes.

Automated summary

In recent years, there has been increased focus on the impact of microbial populations in the gastrointestinal tract on human health and diseases, including cancer. Any alteration in the composition and diversity of the gut microflora has been linked to various pathologies, and the microflora may contribute to tumor initiation and progression through chronic inflammation, toxin production, and metabolite generation. Therefore, identifying the bacterial species involved and their mechanisms of action is crucial for preventing and controlling tumors. Additionally, the microbiome plays a role in the therapeutic potential and adverse effects of anti-cancer approaches, highlighting the importance of personalized medicine.