| Description |
Head and neck squamous cell carcinomas (HNSCC), arising from the mucosal epithelium of the oral cavity, pharynx, and larynx, are the sixth most common cancer worldwide. Alongside smoking, chewing tobacco, heavy alcohol use, and poor oral hygiene, evidence increasingly suggests that polymorphic variability in individual microbiomes can significantly impact cancer phenotypes. The composition of the microbiome, including bacteria, mycoplasmas, viruses, bacteriophages, and archaea, has attracted growing interest due to its potential roles in the development, progression, and treatment of HNSCC. Dysbiosis, an overgrowth of harmful microbes relative to beneficial ones, is associated with chronic inflammation, DNA damage, and immune dysregulation, contributing to cancer development. For instance, alterations in oral bacteria, such as Fusobacteria and Streptococcus, have been identified as potential prognostic biomarkers in HNSCC. In addition, it is also necessary to focus on the gut microbiome, which may initially seem unrelated to tumours in the head and neck region. Microbe-influenced metabolites like inosine, kynurenine, serotonin, shortchain fatty acids, and bile acids can enter the bloodstream and potentially shape the tumour microenvironment (TME) by interacting with receptors on cancer and immune cells. Lastly, the translocation of dysbiotic oral bacteria to the gut can also lead to pathological changes in the gut microbiome. In summary, the interplay between the microbiome and HNSCC pathogenesis highlights the disease's complexity, with dysbiosis in oral and gut microbiota, influenced by diet, lifestyle, and medical interventions, contributing to inflammation, immune dysregulation, metabolic changes, and tumor development.
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