Long-term lifestyle changes after colorectal cancer screening: randomised controlled trial

Objective: There is uncertainty whether cancer screening affects participant incentives for favourable lifestyle. The present study investigates long-term effects of colorectal cancer (CRC) screening on lifestyle changes.

Design: In 1999-2001, men and women drawn from the population registry were randomised to screening for CRC by flexible sigmoidoscopy ('invited-to-screening' arm) or to no-screening (control arm) in the Norwegian Colorectal Cancer Prevention trial. A subgroup of 3043 individuals in the 'invited-to-screening' and 2819 in the control arm, aged 50-55 years, randomised during 2001 had their lifestyle assessed by a questionnaire at inclusion and after 11 years (42% of cohort). The outcome was 11-year changes in lifestyle factors (body weight, smoking status, physical exercise, selected dietary habits) and in total lifestyle score (0-4 points, translating to the number of lifestyle recommendations adhered to). We compared outcomes in the two randomisation arms and attendees with positive versus negative findings.

Results: Total lifestyle scores improved in both arms. The improvement was smaller in the 'invited-to-screening' arm (score 1.43 at inclusion; 1.58 after 11 years) compared with the control arm (score 1.49 at inclusion; 1.67 after 11 years); adjusted difference -0.05 (95% CI -0.09 to -0.01; p=0.03). The change in the score was less favourable in screening attendees with a positive compared with negative screening result; adjusted difference -0.16 (95% CI -0.25 to -0.08; p<0.001).

Conclusions: The present study suggests that possible unfavourable lifestyle changes after CRC screening are modest. Lifestyle counselling may be considered as part of cancer screening programmes.

Trial registration number: NCT00119912.