Red-complex bacteria: immunological background leading to the development of head and neck cancers

Oral microbiome imbalance is involved in the development of head and neck cancers (HNCs). There is a group of oral pathogens, such as Porphyromonas gingivalis , Tannerella forsythia , and Treponema denticola , that creates red-complex. Currently, the oral pathogens’ role in the pathogenesis of periodontitis is well-described; nevertheless, data regarding the link between HNCs and periopathogens are still limited, especially considering T. forsythia and T. denticola . These microbes utilise various virulence factors to promote the carcinogenesis process, affecting the immunological background. This paper presents modern insights into the role of red-complex bacteria in the development of HNCs, concentrating on the immunological aspects.