The Microbiome of Oral Cancer.

The pathogenesis of oral cancer is complex, and not all relevant factors involved in it have been determined. In particular, the role of the microbiota is not well understood because of difficulties in isolating and culturing its organisms. However, the recent development of metagenomic sequencing allows the discovery of all the DNA sequences in a specimen, and thus, the microbiome is now under intensive investigation. Studies of the bacteriome, the mycobiome, and the virome have revealed new organisms and have uncovered various differences between healthy persons and patients with oral cancer. In addition, sequencing of human samples shows the existence of DNA sequences that may be from novel microbes but are actually of unknown origin and so are referred to as the dark matter. The large volumes of data that are being produced by sequencing projects must be studied further to reveal novel pathogens and new pathways in the development of oral cancer.