Associating the oral microbiome across the head and neck cancer continuum: a scoping review.

INTRODUCTION: Head and neck cancers (HNC) comprise oral cavity, oropharynx and larynx tumors. The role of the oral microbiome across the continuum from risk to diagnostic stage and outcomes is not well understood. METHODS: Systematic searches were undertaken; Ovid MEDLINE and Embase, Web of Science and Open Grey (2011-2024), title/abstracts were screened in duplicate. Data were collected using an extraction template and subsequently descriptively analyzed. RESULTS: There were 105 studies included, most from Asia (n = 64, 61%), focusing on oral cavity cancer (n = 58, 55%). Sample sizes were generally small (ranging n = 5-499), with age mainly >50-years (mean n = 102, 97%), and male (n = 4044, 75%). Stage was reported in 63 studies (60%) and survival in 18 (17%). Single clinical sample's were most frequently analyzed (n = 94, 90%). DNA extraction method and primers varied but Illumina technologies were most often employed (n = 73, 70%). Fusobacterium nucleatum most frequently increased in abundance (n = 7, 7%), while Haemophilus parainfluenzae (n = 9, 9%) most frequently decreased in abundance. Over half of studies (n = 58, 55%) provided accessible links to open data. CONCLUSIONS: The abundance of microorganisms in relation to HNC is highly variable. Further large higher quality studies are required to assess the role of microbiome HNC stage, site, and prognosis.