title: Oral microbiome and history of smoking and colorectal cancer.
abstract: BACKGROUND
  The equilibrium of oral microbiome may be altered by environmental factors, including cigarette smoking. Several recent studies also suggest that oral pathogens causing periodontal disease, such asFusobacterium nucleatum, are involved in pathogenesis of colorectal cancer.
  
  
  METHODS
  For this study oral rinse DNA samples from 190 participants in a population-based case-control study for colorectal cancer were used to amplify a V3-V4 region of bacterial 16S rRNA gene. The amplicons were sequenced using Illumina MiSeq paired end chemistry on two runs, yielding approximately 35 million filtered reads which were assigned to bacterial phyla.
  
  
  RESULTS
  No association was found betweenFusobacteriumabundance or presence and colorectal cancer. However, adjusted for age and experimental batch, colorectal cancer history was associated with increased presence of genusLactobacillusand increased relative abundance ofRothiaby 28% and current smoking was associated with a 33% decrease in relative counts of Betaproteobacteria (primarilyNeisseria) and 23% increase in relative abundance ofVeillonellaceaefamily. We also found that smoking had significant effects on the 2ndcomponent scores and 2ndcoordinate distances in principal component and coordinate analyses.
  
  
  CONCLUSIONS
  It remains to be elucidated whether the observed differences can be translated into biochemical changes in oral environment, thus potentially affecting oral health.
authors.affiliation: Department of Oncology and Pathology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Ikuko
authors.initials: I
authors.lastname: Kato
authors.affiliation: Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Adrian A
authors.initials: AA
authors.lastname: Vasquez
authors.affiliation: Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Gregory
authors.initials: G
authors.lastname: Moyerbrailean
authors.affiliation: Department of Oncology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Land
authors.affiliation: Department of Medicine, School of Medicine, University of Illinois at Chicago, IL, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Otolaryngology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Ho-Sheng
authors.initials: HS
authors.lastname: Lin
authors.affiliation: Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Ram
keywords: Cigarette smoking; Colorectal cancer; Oral microbiome