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

Abstract

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.

Keywords: Colorectal neoplasms; Effectiveness; Observational study; Proximal; Screening colonoscopy; Target trial emulation.