Abstract
The past decade has witnessed a surge in epidemiological studies that have explored the relationship between the oral microbiome and oral cancer. Owing to the diversity of the published data, a comprehensive systematic overview of the currently available evidence is critical. This review summarises the current evidence on the metagenomic studies on the oral microbiome in oral cancer. A systematic search was conducted in Medline and Embase databases to identify original studies examining the differences in the oral microbiome of oral cancer cases and controls. A total of twenty-six studies were identified that reported differences in microbial abundance between oral squamous cell carcinoma (OSCC) and controls. Although almost all the studies identified microbial dysbiosis to be associated with oral cancer, the detailed qualitative analysis did not reveal the presence/abundance of any individual bacteria or a consortium to be consistently enriched in OSCC samples across the studies. Interestingly, few studies reported a surge of periodontopathogenic taxa, especially Fusobacteria, whereas others demonstrated a depletion of commensal taxa Streptococci. Considerable heterogeneity could be identified in the parameters used for designing the studies as well as reporting the microbial data. If microbiome data needs to be translated in the future, to complement the clinical parameters for diagnosis and prognosis of oral cancer, further studies with the integration of clinical variables, adequate statistical power, reproducible methods, and models are required.
Highlights
Oral squamous cell carcinoma (OSCC), commonly referred to as oral cancer, is the eighth-most prevalent cancer universally and has a 5-year survival rate of less than 50% [1].In the United States alone, a total of 53,260 new cases and 10,750 deaths were projected for oral and oropharyngeal cancer in 2020 [2]
The search strategy comprised of the following words: “mouth neoplasms”, “oral carcinoma”, “OSCC”, “oral malignancy”, “uncontrol growth”, “bacteria”, “microbiota”, “microbiome”, “metagenomics”, “metagenome”, “sequence analysis”, “DNA”, “RNA”, “ribosomal”, and, “16S”
Our objective was to critically review the studies that investigated the association of the oral microbiome with oral cancer through DNA sequencing of oral samples
Summary
Oral squamous cell carcinoma (OSCC), commonly referred to as oral cancer, is the eighth-most prevalent cancer universally and has a 5-year survival rate of less than 50% [1]. In the United States alone, a total of 53,260 new cases and 10,750 deaths were projected for oral and oropharyngeal cancer in 2020 [2]. The global burden of oral and oropharyngeal cancer on the healthcare system is evident, a clear systematic method of identifying oral cancer at the earliest possible stage is essential, which can ensure prompt treatment administration and higher cure rates. Principal risk factors for oral and oropharyngeal cancers include tobacco use and alcohol consumption [3]. Other factors like genetics, oral health, low socioeconomic status, and human papillomavirus (only for oropharyngeal cancer) play a more minor role [4]. A proportion of oral cancers, especially in Asia, arise in the mucosa bearing long-standing pre-existing changes, visible as distinct clinical lesions, which are collectively termed as “oral potentially malignant disorders (OPMD) [5,6]
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