title: Cigarette smoking and alcohol consumption as risk factors for colorectal adenomatous polyps.
abstract: BACKGROUND
  Results of epidemiologic studies suggest that there is limited evidence for the association between cigarette smoking and risk of colorectal cancer. Cigarette smoking has been shown to increase the risk of colorectal adenomatous polyps, which are recognized as precursors of colorectal cancer, while few studies have examined the association between alcohol consumption and the development of adenomatous polyps.
  
  
  OBJECTIVE
  We examined the association between cigarette smoking, alcohol consumption, and the presence of colorectal adenomatous polyps.
  
  
  METHODS
  Analyses were based on data from a case-control study of dietary and other lifestyle factors for colorectal adenomatous polyps. We assessed the risk of adenomatous polyps associated with total number of years of smoking, number of cigarettes smoked per day, and pack-years of smoking for past and current smokers separately. We also assessed the joint association between cigarette smoking and alcohol consumption on the risk of adenomatous polyps.
  
  
  RESULTS
  Current smokers who smoked more than 20 pack-years were at significantly higher risk of adenomatous polyps compared with never smokers (odds ratio [OR] = 2.56; 95% confidence interval [CI] = 1.28-5.14). Past smokers also had an increased risk of having adenomatous polyps, but no clear trend was observed for pack-years of smoking. Alcohol consumption was positively associated with risk of adenomatous polyps. Compared with nondrinkers, the strongest risk was observed for individuals who consumed 2.31-9.46 g alcohol per day (OR = 2.23; 95% CI = 1.29-3.83), and a decrease in risk was observed for individuals who consumed 9.47-67.36 g alcohol per day (OR = 1.63; 95% CI = 0.92-2.88). Among current smokers, a joint effect was observed for individuals who smoked and drank compared with those who never smoked and were not current drinkers (OR = 4.21; 95% CI = 1.88-9.41). For past smokers, a significant joint effect of smoking and current alcohol consumption was also observed, but the risk was not as strong as that for current smokers (OR = 2.61; 95% CI = 1.40-4.87).
  
  
  CONCLUSIONS
  These data provide further evidence of the positive association between cigarette smoking and the development of colorectal adenomatous polyps. The combination of cigarette smoking and alcohol consumption increased the risk of adenomatous polyps.
  
  
  CONCLUSIONS
  Future research should focus on the understanding of the role of cigarette smoking and alcohol consumption as these two factors relate to the evolution of colorectal adenomatous polyps and subsequent carcinogenesis.
authors.affiliation: University of Texas-Houston Health Science Center, School of Public Health, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Martínez
authors.forename: R S
authors.initials: RS
authors.lastname: McPherson
authors.forename: J F
authors.initials: JF
authors.lastname: Annegers
authors.forename: B
authors.initials: B
authors.lastname: Levin
mesh_terms: D011125:Adenomatous Polyposis Coli / Q000209:etiology*; D018256:Adenomatous Polyps / Q000209:etiology*; D000428:Alcohol Drinking / Q000009:adverse effects*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012004:Rectal Neoplasms / Q000209:etiology*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*