Because the prevalence of proximal colon cancer and APN was higher in older patients15, a greater proportion of advanced colonic neoplasia or cancer would be missed if colonoscopy was not performed for older patients. So if we develop a mixed strategy to offer sigmoidoscopy for younger patients and reserve colonoscopy for older patients, we might be able to detect more APN with fewer colonoscopic procedures. We aimed to determine an optimal cut-off age and choose an appropriate distal sentinel lesion for subsequent colonoscopy.
