Identification of consensus head and neck cancerassociated microbiota signatures: a systematic review and meta- analysis of 16S rRNA and The Cancer Microbiome Atlas datasets

Introduction. Multiple reports have attempted to describe the tumour microbiota in head and neck cancer (HNSC). Gap statement. However, these have failed to produce a consistent microbiota signature, which may undermine understanding the importance of bacterial- mediated effects in HNSC. Aim. The aim of this study is to consolidate these datasets and identify a consensus microbiota signature in HNSC. Methodology. We analysed 12 published HNSC 16S rRNA microbial datasets collected from cancer, canceradjacent and noncancer tissues to generate a consensus microbiota signature. These signatures were then validated using The Cancer Microbiome Atlas (TCMA) database and correlated with the tumour microenvironment phenotypes and patient's clinical outcome. Results. We identified a consensus microbial signature at the genus level to differentiate between HNSC sample types, with cancer and canceradjacent tissues sharing more similarity than noncancer tissues. Univariate analysis on 16S rRNA datasets identified significant differences in the abundance of 34 bacterial genera among the tissue types. Paired cancer and canceradjacent tissue analyses in 16S rRNA and TCMA datasets identified increased abundance in Fusobacterium in cancer tissues and decreased abundance of Atopobium, Rothia and Actinomyces in canceradjacent tissues. Furthermore, these bacteria were associated with different tumour microenvironment phenotypes. Notably, high Fusobacterium signature was associated with high neutrophil (r=0.37, P<0.0001), angiogenesis (r=0.38, P<0.0001) and granulocyte signatures (r=0.38, P<0.0001) and better overall patient survival [continuous: HR 0.8482, 95 % confidence interval (CI) 0.7758-0.9273, P=0.0003]. Conclusion. Our meta- analysis demonstrates a consensus microbiota signature for HNSC, highlighting its potential importance in this disease.