Microbiome and pancreatic cancer: A comprehensive topic review of literature

Table 1 Oral microbiome and pancreatic cancer

Ref.	Study design	Case No.	Control No.	Detection	Bacteria association	Outcome	Author conclusion
				Method
Michaud et al[18], 2013, Western Europe	Prospective	405	416	Plasma IgG	Porphyromonas gingivalis ATTC 53978	High titer P. gingivalis (IgG > 200 ng/mL)	Two fold increase in pancreatic cancer among individuals with high titer P. gingivalis
						OR 2.14
						P = 0.05
					High titer, commensal bacteria	OR = 0.55	45% lower risk of pancreatic cancer compared to individuals with lower antibody levels
						95%CI: 0.36-0.83
Farrell et al[12], 2012, United States	Case-control	28	28	Salivary qPCR, Microarray	Neisseria elongata and Streptococcus mitis	N. elongata and S. mitis significantly decreased	N. elongate and S. mitis combination ROC plot AUC 0.90 serves as 96% sensitive, 82% specific biomarker for pancreatic ca vs. healthy subjects
						ROC-plot AUC 0.90;
						95%CI: 0.78-0.96, P < 0.0001
					Granulicatella adiacens	G. adiacens
						Significantly elevated compared to healthy control
Lin et al[24], 2013, United States	Pilot	13	12	Salivary rRNA	Bacteroides genus	More common pancreatic cancer patient vs healthy subjects	Oral flora alterations in microbiome in pancreatic cancer exist compared to healthy individuals
						P = 0.002
					Corynebacterium genus Aggregatibacter genus	Less common in pancreatic cancer vs healthy subjects P = 0.033 and 0.019
Torres et al[25], 2015 United States	Cross-sectional	8	22	Salivary rRNA, PCR	Higher Leptotrichia and lower Porphyromonas colonization	Lepotrichia:Porphyromonas ratio elevated in pancreatic cancer vs healthy control P = 0.001	L:P ratio may be reliable biomarker for pancreatic cancer diagnosis
Fan et al[26], 2016 United States	Nested Case control	361	371	Salivary rRNA gene sequencing	Oral pathogens	P. gingivalis	Presence of oral pathogens are related to subsequent increased risk of pancreatic cancer. On contrary, Fusobacteria and Leptotrichia are associated with dose or concentration dependent decrease risk of pancreatic cancer
					P. gingivalis,	AOR = 1.60
					A. actinomycetemcomitans	(95%CI: 1.15-2.22)
						A. actinomycetes
						OR = 2.20
						(95%CI: 1.16-4.18)
					Fusobacteria and Leptotrichia	Fusobacteria
						decreased risk
						OR per percent increase of relative
						Abundance
						OR = 0.94
						(95%CI: 0.89-0.99)
						Lepotrichia
						OR = 0.87
						(95%CI: 0.79-0.95)