National Polyp Study

The National Polyp Study followed 2,602 patients whose adenomas had been removed at colonoscopy. After a median 15.8 years, 1,246 had died of any cause and 12 of colorectal cancer, against 25.4 deaths expected from Surveillance, Epidemiology and End Results rates: a standardised incidence-based mortality ratio of 0.47 (95% CI 0.26 to 0.80), a 53 percent reduction. Mortality from colorectal cancer in the first ten years after polypectomy was the same as in the internal control group of people with non-adenomatous polyps. The study is the evidence that the adenoma-carcinoma sequence can be interrupted mechanically, which is the whole basis of colonoscopic screening and of the surveillance intervals that follow polypectomy.