Oral Microbiota Associated with Oral and Gastroenteric Cancer

Table 7: Oral bacteria associated with healthy controls in the gastric and colorectal studies

Cancer	Phylum	Genus/species	Main findings	N	Technology used	Case sample	Control sample	Reference
GA	Bacteroidetes	Porphyromonas	Relative abundance decreased in GA samples compared to healthy control samples	57 newly diagnosed GA, and 80 healthy controls	16S rRNA pyrosequencing	Tongue coating sample from patients	Tongue coating sample from healthy controls	Wu et al., 2018 [⁸³]
	Bacteroidetes	Prevotella
	Proteobacteria	Neisseria
	Bacteroidetes	Porphyromonas	Relative abundance decreased in GA samples compared to healthy control samples	34 patients, and 17 healthy controls	16S rRNA sequencing	Tongue coating sample from patients	Tongue coating sample from healthy controls	Hu et al., 2015 [⁸²]
	Fusobacteria	Fusobacterium
	Proteobacteria	Neisseria
CRC	Proteobacteria	Neisseria	Relative abundance decreased in CRC samples compared to healthy samples	99 colorectal cancer patients, 32 colorectal polyps patients, and 103 healthy controls	16S rRNA sequencing	Saliva samples from cancer patients	Saliva and faecal samples from controls	Flemer et al., 2017 [⁷⁸]
CRC	Fusobacteria	F. nucleatum	Detected also in control healthy subjects		16S rRNA sequencing	Saliva samples from cancer patients	Saliva and faecal samples from controls	Flemer et al., 2017 [⁷⁸]