Long-lasting reduction of risk of colorectal cancer following screening endoscopy

Several studies have suggested that incidence and mortality of colorectal cancer (CRC) may be strongly reduced for up to 10 years by endoscopic screening with removal of precancerous lesions, but so far there are no data on risk reduction beyond this period. We assessed long-term reduction of CRC risk following screening endoscopy in a statewide population-based case-control study in Saarland, Germany. Lifetime history of screening endoscopy was compared between 320 cases with CRC aged 45-80 and 263 controls with other forms of cancer recruited from the same population. Potential confounding factors were controlled for by multiple logistic regression. 11% of cases compared to 27% of controls had a history of endoscopy for screening purposes (adjusted odds ratio (OR) = 0.28, 95% confidence interval (CI): 0.16-0.48). This strong risk reduction was also seen (OR = 0.41, 95% CI: 0.19-0.89) in subjects who had their last screening endoscopy more than 10 years ago (median: 18.9 years). Long term (> 10 years since last screening) risk reduction appeared to be particularly strong for advanced (Dukes C or D) CRC (OR = 0.19, 95% CI: 0.06-0.64). We conclude that risk reduction by screening endoscopy is long lasting, in particular with respect to advanced CRC.