Impact of colorectal cancer screening on future lifestyle choices: a three-year randomized controlled trial

Clin Gastroenterol Hepatol. 2007 Apr;5(4):477-83. doi: 10.1016/j.cgh.2006.12.011. Epub 2007 Mar 23.


Background & aims: 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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Attitude to Health*
  • Choice Behavior
  • Colorectal Neoplasms / prevention & control*
  • Confidence Intervals
  • Female
  • Humans
  • Life Style*
  • Male
  • Mass Screening / methods*
  • Middle Aged
  • Norway
  • Obesity / epidemiology
  • Occult Blood
  • Probability
  • Reference Values
  • Risk Factors
  • Sex Factors
  • Sigmoidoscopy / methods
  • Smoking / epidemiology