Screening colonoscopy similarly prevented distal and proximal colorectal cancer: a prospective study among 55-69-year-olds.

OBJECTIVES

We aimed to evaluate the effectiveness of screening colonoscopy in reducing incidence of distal vs. proximal colorectal cancer (CRC) in persons aged 55-69 years.

STUDY DESIGN AND SETTING

Using observational data from a German claims database (German Pharmacoepidemiological Research Database), we emulated a target trial with two arms: Colonoscopy screening vs. no-screening at baseline. Adjusted cumulative incidence of total, distal, and proximal CRC over 11 years of follow-up was estimated in 55-69-year-olds at an average CRC risk and without colonoscopy, polypectomy, or fecal occult blood test before baseline.

RESULTS

Overall, 307,158 persons were included (screening arm: 198,389 and control arm: 117,399). The adjusted 11-year risk of any CRC was 1.62% in the screening group and 2.38% in the no-screening group resulting in a relative risk of 0.68 (95% CI: 0.63-0.73). The relative risk was 0.67 for distal CRC (95% CI: 0.62-0.73) and 0.70 (95% CI: 0.63-0.79) for proximal CRC. The cumulative incidence curves of the groups crossed after 6.7 (distal CRC) and 5.0 years (proximal CRC).

CONCLUSION

Our results suggest that colonoscopy is effective in preventing distal and proximal CRC. Unlike previous studies not using a target trial approach, we found no relevant difference in the effectiveness by location.