Original article
Impact of Colorectal Cancer Screening on Future Lifestyle Choices: A Three-Year Randomized Controlled Trial

https://doi.org/10.1016/j.cgh.2006.12.011Get rights and content

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.

Section snippets

Design and Study Population

A flowchart with details on allocation, exclusions, nonattendees, and nonresponders is given in Figure 1. Those invited for screening (n = 6961) and controls (n = 7000) were randomly drawn from the population registry. The screening group was invited to a once only flexible sigmoidoscopy (FS) examination or a combination of once only FS and an FOBT (1:1), whereas the control group did not receive any intervention. The groups consisted of men and women (1:1) born between 1946–1950 (age 50–55

Results

Of the baseline responders (n = 8485), 83% (n = 7060) completed the follow-up survey (Figure 1). Among those classified as lost to follow-up (n = 137), 52 persons were deceased, 30 had emigrated, 38 were unreachable as a result of unknown address, and 17 persons asked to be withdrawn from the study. The response rates for the follow-up questionnaire among eligible baseline responders (n = 8348) were 84% (3462/4139) and 85% (3598/4209) for controls and screened group, respectively.

Mean values

Discussion

The present study has demonstrated undesirable lifestyle changes associated with CRC screening. Subjects invited to screening reduced their intake of fruit, berries, and vegetables, did not follow the trend of increased frequency of physical exercise seen for controls, gained more weight, and did not improve their smoking habits as successfully as did the controls not invited for screening. Also, normal findings at screening (no neoplasia) were associated with a subsequent statistically

Conclusion

In the present study, 50- to 55-year-old individuals invited to FS screening for colorectal neoplasia had poorer improvement in smoking habits, poorer increase in the total score of exercise, poorer increase in the intake of fruit, berries, and vegetables per day, and a higher increase in body weight compared with controls not invited to screening. The importance of this in terms of future lifestyle-related morbidity and deaths is not clear, but it might represent a considerable educational

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Supported by the Norwegian Cancer Society and the Norwegian Department of Health.

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