KEGG analyses also identified 6 pathways, including IL‐17 signalling pathway, C‐type lectin receptor signalling pathway, TNF signalling pathway, Leishmaniasis, Rheumatoid arthritis, and NF‐kB signalling pathway, in P. gingivalis‐mediated HNSCC metastasis that may be relevant to P. gingivalis infection in HNSCC. This evidence concerns the gene TNF and rheumatoid arthritis.