Oral Microbiota and Tumor—A New Perspective of Tumor Pathogenesis Original paper

What was studied?

This review article focuses on the role of oral microbiota in tumor pathogenesis. It explores how oral microbiota, typically associated with local oral diseases, can influence distant tumors through mechanisms like immune modulation, chronic inflammation, and DNA mutations. The study further examines how oral pathogens can either directly or indirectly drive carcinogenesis, influencing the initiation, development, and progression of tumors. It highlights the microbial components of the oral cavity that are implicated in tumorigenesis, particularly the bacteria Fusobacterium nucleatum and Porphyromonas gingivalis, and discusses their involvement in various cancers, including oral, colorectal, and gastric cancers.

Who was studied?

The article synthesizes findings from multiple studies involving patients diagnosed with various cancers, especially oral cancers and gastrointestinal cancers. It examines how shifts in the oral microbiota, particularly an imbalance in bacterial populations (dysbiosis), correlate with tumor formation and progression. The studies reviewed include both clinical trials and animal models that have explored the microbiome in relation to cancer. These studies highlight the impact of oral pathogens, such as Fusobacterium nucleatum and Porphyromonas gingivalis, in driving tumor progression, immune evasion, and metastasis.

Most important findings

The review emphasizes several key findings regarding the role of the oral microbiota in cancer. It identifies how microbial communities in the oral cavity can translocate to distant organs via the bloodstream or digestive tract, contributing to cancer progression. Specific bacteria, like Fusobacterium nucleatum and Porphyromonas gingivalis, are linked to various stages of tumor development, with these pathogens playing a role in immune suppression and chronic inflammation. Fusobacterium nucleatum, for instance, activates inflammatory pathways that promote colorectal cancer progression. Moreover, the article highlights the importance of oral microbiota in the regulation of tumor microenvironments, where certain microbes enhance tumor progression by altering immune responses, while others have the potential to inhibit tumor growth by activating antitumor immunity. The review also points out the relationship between oral microbiota composition and the efficacy of cancer treatments, particularly how microbes can affect the response to chemotherapy and immunotherapy.

Key implications

The review suggests that the oral microbiota could be a crucial factor in cancer diagnosis, prognosis, and treatment. The presence of specific oral bacteria in the tumor microenvironment can potentially serve as biomarkers for cancer detection or to predict therapeutic outcomes. The manipulation of oral microbiota through probiotics, antibiotics, or other microbiome-targeted interventions could offer novel approaches for enhancing cancer treatment, particularly in immunotherapy. However, further research is needed to better understand the specific mechanisms through which oral microbiota influence tumor progression and therapeutic efficacy. The article advocates for deeper studies into how dysbiosis in the oral microbiota may contribute to systemic diseases like cancer and how modifying the microbiota could prevent or treat these diseases.