What Is the Optimal Interval for Screening Colonoscopy?
At 5-year repeat colonoscopy, only 1% of 1250 participants had advanced neoplasms.
U.S. guidelines generally recommend a 10-year interval after a normal initial screening colonoscopy, but the optimal interval is uncertain. In this study, researchers examined the prevalence of abnormalities among employees of a company that offered routine colonoscopic screening at 5-year intervals.
A total of 2436 asymptomatic people (age, 50) had no adenomas on first-time screening colonoscopy; 1256 of them returned for rescreening at 5 years. One or more neoplastic polyps were found in 201 (16%) of these rescreened people, but only 16 (1.3%) had advanced neoplasms (tubular adenomas 1 cm, polyps with a villous component, or polyps with high-grade dysplasia).
Comment: In this study, people for whom initial screening colonoscopy results were normal had a very low prevalence of advanced neoplasia on 5-year follow-up colonoscopy. These findings suggest that the rescreening interval should be at least 5 years. For policy makers, a more relevant study would be a randomized trial in which 5-year and 10-year intervals are compared, but the requirement for long-term enrollment would make such a trial difficult to complete successfully. For now, we have no reason to change screening guidelines in the U.S.
Allan S. Brett, MDPublished in Journal Watch General Medicine September 23, 2008Citation(s):Imperiale TF et al. Five-year risk of colorectal neoplasia after negative screening colonoscopy. N Engl J Med 2008 Sep 18; 359:1218.