What is the yield of screening colonoscopy 5 years after an initially normal examination result?

Five years after a normal colonoscopy result, a second examination detected no cancers and only 16 of 1256 patients had an advanced neoplastic polyp. The risk that those "advanced polyps" will progress to cancer is only approximately 1% per year (Gastroenterology 1987;93:1009-13), so a 10-year interval as currently recommended by most organizations is perfectly reasonable and appears to provide a good balance between risk, benefit, and cost. An even longer interval may be reasonable if we can define low-risk patients on the basis of personal habits, family history, or genetics. (LOE = 2b)

Imperiale TF, Glowinski EA, Lin-Cooper C, et al. Five year risk of colorectal neoplasia after negative screening colonoscopy. N Engl J Med 2008;359(12):1218-1224.  [PMID:18799558]

Cohort (retrospective)

Government

Outpatient (any)

Current recommendations for colonoscopy generally suggest a 10-year interval, although the United States Preventive Services Task Force did not specify an interval because of a lack of good data. This study used a registry of 36 endoscopists in Indiana to identify adults older than 50 years without serious bowel disease who had a normal initial colonoscopy result (N = 2436). The screening program routinely recommended a second examination 5 years after an initial normal examination result, and 1256 patients (51.6%) complied. The researchers attempted to contact the patients who did not have a follow-up colonoscopy, but only received responses from 26%. No patients died of interval colon cancer based on death registry data. The second colonoscopy identified no adenocarcinomas (95% CI, 0 - 0.24%) and only 19 advanced adenomas in 16 persons (1.3%), defined as a tubular adenoma of at least 10 mm, a polyp with at least 25% villous component, and any polyp with high-grade dysplasia. Among all 1256 patients screened, 79 would need to be rescreened at 5 years to detect an advanced adenoma. Among men, 55 would need to be rescreened; 182 women, however, would need to be rescreened. For persons with hyperplastic polyps on baseline colonoscopy, the number needed to screen would be 50; among those with no polyps at baseline the number needed to screen would be 88.