title: A prospective cohort study of rectal cancer risk in relation to active cigarette smoking and passive smoke exposure.
abstract: OBJECTIVE
  The present investigation prospectively examined active cigarette smoking and household passive smoke exposure and the risk of developing rectal cancer.
  
  
  METHODS
  Cigarette smoking data were collected on all household members during two private censuses in Washington County, Maryland. These two cohorts were followed up, one cohort from 1963-1978 and the other from 1975-1994 for first-time diagnoses of rectal cancer. We identified 148 and 169 rectal cancer cases in the 1963 and 1975 cohorts, respectively. Relative risks were estimated by means of Poisson regression models.
  
  
  RESULTS
  In men, the adjusted relative risks (aRR) and 95% confidence intervals (CI) for the association between current smoking and rectal cancer were 3.1 (1.2-7.8) in the 1963 cohort and 1.8 (0.9-3.7) in the 1975 cohort; the corresponding aRRs in women were 0.9 (0.5-1.8) and 1.6 (0.9-3.8) in the 1963 and 1975 cohorts, respectively. In nonsmokers, household passive smoke exposure was strongly associated with rectal cancer among men in the 1963 cohort (aRR = 5.8; 1.8-18.4) but not the 1975 cohort (aRR = 1.1; 0.2-5.0). In women, household passive exposure was not strongly associated with rectal cancer in either cohort.
  
  
  CONCLUSIONS
  The results of our study suggest that active cigarette smoking may contribute to rectal cancer risk, but inconsistencies in the findings preclude drawing strong, clear-cut inferences.
authors: Johns Hopkins Sidney Kimmel Comprehensive Cancer Center, Baltimore, Maryland, USA.
authors: Craig M
authors: CM
authors: Hooker
authors: Lisa
authors: L
authors: Gallicchio
authors: Jeanine M
authors: JM
authors: Genkinger
authors: George W
authors: GW
authors: Comstock
authors: Anthony J
authors: AJ
authors: Alberg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008396:Maryland; D008875:Middle Aged; D016017:Odds Ratio; D011446:Prospective Studies; D012004:Rectal Neoplasms / Q000453:epidemiology*; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects*; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution