title: Impact of colorectal cancer screening on future lifestyle choices: a three-year randomized controlled trial.
abstract: OBJECTIVE
  A potential downside of colorectal cancer screening is that a "health certificate effect" might have negative effects on lifestyle. The aim of the present randomized controlled trial was to evaluate lifestyle changes in a group of individuals offered flexible sigmoidoscopy screening compared with a control group and also in relation to screening outcome.
  
  
  METHODS
  Men and women aged 50-55 years were drawn by randomization from the population registry to be invited for flexible sigmoidoscopy screening (n = 6961) or not to be invited (n = 7000). Both groups were asked to fill in a questionnaire on selected lifestyle indicators at baseline and 3 years later. From both rounds, 3598 pairs of completed questionnaires were available for analysis from the screening group and 3462 from the control group.
  
  
  RESULTS
  Both groups revealed a desirable change in most lifestyle indicators. A weight gain in the screening group was, on average, 0.24 kg higher than in the control group (P = .023). The screening group had poorer improvement in score for smoking (mean difference, 0.05; P = .013) and exercise habits (mean difference, -0.12; P = .001) and a lower increase in servings/day of fruit, berries, and vegetables (mean difference, -0.10; P = .001) compared with controls. The weight gain in screen-negative individuals (ie, no neoplasia) was, on average, 0.5 kg (P = .020) more than for screen positives.
  
  
  CONCLUSIONS
  The present study has demonstrated a possible health certificate effect of flexible sigmoidoscopy screening and screening outcome on lifestyle. Although modest, these findings indicate a potential need for patient education in screening programs.
authors.affiliation: The Cancer Registry of Norway, Institute of Population-based Cancer Research, Montebello, Norway.
authors.forename: Inger K
authors.initials: IK
authors.lastname: Larsen
authors.forename: Tom
authors.initials: T
authors.lastname: Grotmol
authors.forename: Kari
authors.initials: K
authors.lastname: Almendingen
authors.forename: Geir
authors.initials: G
authors.lastname: Hoff
mesh_terms: D000367:Age Factors; D001294:Attitude to Health; D002755:Choice Behavior; D015179:Colorectal Neoplasms / Q000517:prevention & control*; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D009664:Norway; D009765:Obesity / Q000453:epidemiology; D009780:Occult Blood; D011336:Probability; D012016:Reference Values; D012307:Risk Factors; D012737:Sex Factors; D012812:Sigmoidoscopy / Q000379:methods; D012907:Smoking / Q000453:epidemiology