Salivary Microbiota Composition in Patients with Oral Squamous Cell Carcinoma: A Systematic Review

SIMPLE SUMMARY: This review aimed to analyse the current knowledge regarding the composition of salivary microbiota of patients with oral squamous cell carcinoma (OSCC). The protocol for this study was designed following the PRISMA guidelines. Observational studies, in human subjects with histological diagnosis of OSCC, concerning the analysis of salivary microbiota, were selected. Eleven papers were included. The salivary microbiomes of 1335 patients were analysed. Periodontal pathogens were the most frequent bacteria detected in patients with OSCC. We have found that although there are evident alterations in the composition of the salivary microbiota in OSCC patients, due to the great heterogeneity of the studies, it is still a challenge to identify a specific microbiota pattern. If the associations between alterations in the salivary microbiome and OSCC are confirmed, microbiome analysis could represent a useful tool for the screening and follow-up of patients affected by OSCC. ABSTRACT: Background: Oral squamous cell carcinoma (OSCC) is one of the most prevalent cancers worldwide. Despite recent advances in diagnosis and treatment, in recent years, an increase in the incidence of OSCC has been registered, and the mortality rate is still high. This systematic review aims to identify a potential association between the composition of salivary microbiota and OSCC. Materials and Methods: The protocol for this study was designed following the PRISMA guidelines. Records were identified using different search engines (e.g., Medline/PubMed). Observational studies, in human subjects with histological diagnosis of OSCC, concerning the analysis of salivary microbiota, were selected. Results: Eleven papers were included. The salivary microbiomes of 1335 patients were analysed (n.687 OSCC and n.648 controls). Due to the great heterogeneity of the studies, it was not possible to profile a specific microbiota associated with OSCC. However, periodontal pathogens were the most common bacteria detected in patients with OSCC (i.e., Fusobacterium, Prevotella). Conclusions: Although there are evident alterations in the salivary microbiota composition in OSCC patients, it is still a challenge to identify a specific microbiota pattern in OSCC patients. If the associations between specific salivary microorganisms and OSCC are confirmed, microbiome analysis could be a useful tool for the screening and follow-up of patients affected by OSCC.