Potential Role of the Intratumoral Microbiota in Prognosis of Head and Neck Cancer

The tumor microbiome, a relatively new research field, affects tumor progression through several mechanisms. The Cancer Microbiome Atlas (TCMA) database was recently published. In the present study, we used TCMA and The Cancer Genome Atlas and examined microbiome profiling in head and neck squamous cell carcinoma (HNSCC), the role of the intratumoral microbiota in the prognosis of HNSCC patients, and differentially expressed genes in tumor cells in relation to specific bacterial infections. We investigated 18 microbes at the genus level that differed between solid normal tissue (<i>n</i> = 22) and primary tumors (<i>n</i> = 154). The tissue microbiome profiles of <i>Actinomyces</i>, <i>Fusobacterium</i>, and <i>Rothia</i> at the genus level differed between the solid normal tissue and primary tumors of HNSCC patients. When the prognosis of groups with rates over and under the median for each microbe at the genus level was examined, rates for <i>Leptotrichia</i> which were over the median correlated with significantly higher overall survival rates. We then extracted 35 differentially expressed genes between the over- and under-the-median-for<i>-Leptotrichia</i> groups based on the criteria of >1.5 fold and <i>p</i> < 0.05 in the Mann–Whitney U-test. A pathway analysis showed that these <i>Leptotrichia</i>-related genes were associated with the pathways of Alzheimer disease, neurodegeneration-multiple diseases, prion disease, MAPK signaling, and PI3K-Akt signaling, while protein–protein interaction analysis revealed that these genes formed a dense network. In conclusion, probiotics and specific antimicrobial therapy targeting <i>Leptotrichia</i> may have an impact on the prognosis of HNSCC.