Role of the oral microbiota in cancer evolution and progression

Abstract

Bacteria identified in the oral cavity are highly complicated. They include approximately 1000 species with a diverse variety of commensal microbes that play crucial roles in the health status of individuals. Epidemiological studies related to molecular pathology have revealed that there is a close relationship between oral microbiota and tumor occurrence. Oral microbiota has attracted considerable attention for its role in in‐situ or distant tumor progression. Anaerobic oral bacteria with potential pathogenic abilities, especially Fusobacterium nucleatum and Porphyromonas gingivalis, are well studied and have close relationships with various types of carcinomas. Some aerobic bacteria such as Parvimonas are also linked to tumorigenesis. Moreover, human papillomavirus, oral fungi, and parasites are closely associated with oropharyngeal carcinoma. Microbial dysbiosis, colonization, and translocation of oral microbiota are necessary for implementation of carcinogenic functions. Various underlying mechanisms of oral microbiota‐induced carcinogenesis have been reported including excessive inflammatory reaction, immunosuppression of host, promotion of malignant transformation, antiapoptotic activity, and secretion of carcinogens. In this review, we have systemically described the impact of oral microbial abnormalities on carcinogenesis and the future directions in this field for bringing in new ideas for effective prevention of tumors.

Local and systemic mechanisms linking periodontal disease and inflammatory comorbidities

“…Besides F. nucleatum , several other oral bacteria are suspected to play a role in different types of carcinoma (reviewed in ref. 119 ).…”

“…Amyloid-β plaque www.nature.com/nri activate the inhibitory immunoreceptor T cell immunoreceptor with immunoglobulin and ITIM domains (TIGIT), thereby enabling the tumour cells to evade killing by T cells and natural killer cells10 . Besides F. nucleatum, several other oral bacteria are suspected to play a role in different types of carcinoma (reviewed in reF 119. ).…”

Global Analysis of Microbiota Signatures in Four Major Types of Gastrointestinal Cancer

“…The microbiota interacts with different types of host cells to modulate the organ microenvironment and to regulate physiological functions (8). Pathophysiological changes in cells and alterations in the microbial signature could have a significant impact on tumor occurrence and progression (9,10), especially as microbial colonization is highly site-specific, allowing them to modulate the tumor microenvironment. The bacterial effects on cancer progression are related to the time and location of colonization (11), as well as on other pathogenic factors.…”

The Role of the Oral Microbiota in the Etiopathogenesis of Oral Squamous Cell Carcinoma

“…Many species of anaerobic bacteria have been proposed to be involved in carcinogenesis [ 10 ]. Nagy et al detected significantly higher amounts of Porphyromonas and Fusobacterium in OSCC tissue samples compared to samples from healthy mucosa [ 11 ].…”

“…Most aerobic bacteria are located in the superficial regions of the oral cavity and act as commensal microorganisms maintaining microbial balance. Only a few species of aerobic bacteria have been reported to have pathogenic properties [ 10 ].…”