Oral dysbiosis in the onset and carcinogenesis of oral epithelial dysplasia: A systematic review

Specific Oral Microbial Differences in Proteobacteria and Bacteroidetes Are Associated with Distinct Sites When Moving from Healthy Mucosa to Oral Dysplasia—A Microbiome and Gene Profiling Study and Focused Review

“…This, however, may indicate that other species, such as Phorphyromonas gingivalis, may be responsible for the production of N-nitroso compounds, which have been associated with increased risk of OSCC [71]. In a recent study (2023), Shen et al [26] systematically reviewed the literature on the oral microbiome in dysplasia tissues and found that the analyzed studies presented a high risk of bias due to non-negligible heterogeneity in the type and size of the sample and inconsistent oral microbiome composition, strongly limiting the analysis. However, out of the 11 selected studies, only 6 of those histopathologically diagnosed dysplasia in the tissues, 1 of which (Herreros-Pomares et al [73]) did not control for dysplasia and mixed the non-dysplasia samples with mild, moderate, and severe dysplasia samples.…”

“…Our group previously identified a high Fusobacterial and low Streptococcal phenotype as part of the transition from health to primary and metastatic oral and head and neck cancer [ 16 ]. Additionally, a recent metadata analysis on oral epithelial dysplasia indicates increases in the Bacteroidetes phylum in dysplasia patients and increases in the Fusobacterium genus in both dysplasia and OSCC patients [ 26 ]. Thus, this study complements previous findings by showing that increases in Proteobacteria and Fusobacteria and decreases in Firmicutes are associated with the changes from health to oral dysplasia and to carcinogenesis.…”

“…Dysbiosis is often characterized by a combination of reduced overall microbial diversity and negative changes in the relative abundances of beneficial and pathogenic microbes/bacteria [ 13 , 25 ]. Thus far, studies have demonstrated for dysplasia, in particular, a significant decrease in commensal bacteria, such as the Streptococci genus, and an simultaneous increase in pathogenic bacteria, mainly Bacteroidetes phyla and the Fusobacterium genus [ 26 , 27 ]. Moreover, epidemiologic studies have further demonstrated an association between periodontal disease/periodontal pathogens and oral and orodigestive cancers [ 15 , 28 , 29 , 30 ].…”

“…Most studies in the field compare the oral microbiome of oral dysplasia tissues to either histologically normal adjacent/contralateral tissues or to whole mouth rinses or saliva from healthy patients [ 31 , 32 , 33 , 34 , 35 , 36 ]. Moreover, a recent meta-analysis specifically on oral dysplasia [ 26 ] indicates a high-risk of bias due to non-negligible heterogeneity of specimen types.…”

Oral Bacteria, Virus and Fungi in Saliva and Tissue Samples from Adult Subjects with Oral Squamous Cell Carcinoma: An Umbrella Review

“…Data from 32 studies on the microbiological content (bacteria, viruses, or fungi) of saliva or OSCC samples in adult subjects (>18 years of age) with OSCC diagnosed through clinical examination and confirmed based on histopathologic analysis were extracted and qualitatively synthesized in two tables: Table 1 reports data from studies that evaluated the microbial content of OSCC samples and Table 2 reports data from studies that evaluated the microbial content of saliva in subjects with OSCC. Data from included studies [35,42,43,45,47,52,54,55,58,64] that evaluated both types of samples were divided and reported separately in the corresponding tables. Only data compliant with the eligibility criteria were extracted, so data from other types of non-OSCC cancers, from districts different from the oral cavity, or from pediatric subjects were not considered.…”