title: Partial associations of dietary iron, smoking and intestinal bacteria with colorectal cancer risk.
abstract: Smoking and high red meat intake have been associated with colorectal cancer (CRC) risk. Increased iron exposure may be a common factor, favoring the colonization of certain bacterial pathogens that preferentially grow in an iron-rich luminal environment. We analyzed the data from a population-based case-control study of CRC and measured antibody levels against flagelin of Salmonella (FliC), one of the irontrophic bacteria, in 2 independent blood collections. The risk of CRC synergistically increased by combined exposures to heme iron intake and pack-yr (PY) of cigarette smoking (P value for the interaction = 0.039 on the continuous scale). There was a marginally significant interaction between heme iron intake and PY in increasing FliC antibody in the U.S. control subjects (P = 0.055), although no iron or smoking data were available for Dutch samples. Furthermore, FliC antibody levels were significantly higher in patients with colorectal polyps and cancer than in controls in both Dutch (3.93 vs. 2.23) (P = 0.014) and U.S. samples (6.65 vs. 4.37) (P < 0.001). Potential roles of iron from cigarette smoking and dietary heme in CRC through altering irontrophic luminal bacterial population may warrant further investigation.
authors: Karmanos Cancer Institute, and Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA. katoi@karmanos.org
authors: Ikuko
authors: I
authors: Kato
authors: Annemarie
authors: A
authors: Boleij
authors: Guus A M
authors: GA
authors: Kortman
authors: Rian
authors: R
authors: Roelofs
authors: Zora
authors: Z
authors: Djuric
authors: Richard K
authors: RK
authors: Severson
authors: Harold
authors: H
authors: Tjalsma
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000382:microbiology; D005260:Female; D005408:Flagellin / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000382:microbiology*; D019266:Iron, Dietary / Q000008:administration & dosage / Q000009:adverse effects*; D008297:Male; D008824:Michigan / Q000453:epidemiology; D008875:Middle Aged; D015999:Multivariate Analysis; D009426:Netherlands / Q000453:epidemiology; D016017:Odds Ratio; D012307:Risk Factors; D012475:Salmonella / Q000378:metabolism / Q000472:pathogenicity; D012907:Smoking / Q000009:adverse effects*
chemical_list: D019266:Iron, Dietary; D005408:Flagellin