Oral Microbiota and Head and Neck Cancer: Carcinogenic Mechanisms and Biomarkers

Resumo

Cancer remains a significant global health problem, and the role of microorganisms in carcinogenesis has been increasingly investigated. The oral microbiota, due to its anatomical proximity and potential for translocation, emerges as a factor of interest in head and neck oncogenesis. This narrative review aims to synthesize and discuss, based on the provided literature, the associations between the oral microbiota and head and neck cancer, with emphasis on proposed carcinogenic mechanisms and biomarker potential. This is a narrative literature review constructed from the critical analysis and qualitative synthesis of seven original and review scientific articles provided as the exclusive data source. The findings indicate a consistent association of oral squamous cell carcinoma with bacteria such as Porphyromonas gingivalis, Fusobacterium nucleatum, Streptococcus mutans, and other Streptococcus species, in addition to Epstein–Barr virus, human herpesvirus 8, herpes simplex virus type 1, human papillomavirus, and the yeast Candida albicans. In nasopharyngeal carcinoma, Epstein–Barr virus and the translocation of oral bacteria such as Fusobacterium nucleatum and Prevotella intermedia into tumor tissue stand out. Identified carcinogenic mechanisms include: production of oncogenic metabolites (such as kynurenic acid by S. mutans), activation of the aryl hydrocarbon receptor, CD8+ T lymphocyte exhaustion, immunosuppressive reprogramming of the tumor microenvironment, induction of cancer stem cells, stress-induced dysbiosis, and bacterial translocation to extraoral sites. The oral microbiota plays a multifactorial role in head and neck carcinogenesis, acting through direct mechanisms (tumor colonization, production of oncometabolites) and indirect mechanisms (immune modulation, interaction with oncogenic viruses). The identification of specific microorganisms and their metabolites in the tumor microenvironment and saliva offers potential for the development of early diagnostic biomarkers and therapeutic targets.