In the EPoS II trial, 10,799 patients in eight European countries who had previously had high-risk adenomas removed were randomised to a first follow-up colonoscopy after three or five years. After five years of follow-up, 0.77% of the five-year group had developed cancer, compared with 0.82% of the three-year group, with no clear difference in cancer stage. The five-year group underwent nearly 4,200 fewer examinations. In the parallel EPoS III study of 1,861 patients with serrated polyps, about 1% developed colorectal cancer after five years and none died from it.

Hans-Olov Adami, Professor Emeritus at KI’s Department of Medical Epidemiology and Biostatistics, who coordinated the Swedish part of the project, said: “The results suggest that we need to reassess when these patients should be called in for their next colonoscopy.”