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What Is the Appropriate Screening Interval After Negative Colonoscopy?

Longitudinal data support a 10-year interval between colonoscopies in low-risk patients.

The recommendation that screening colonoscopy need not be repeated for 10 years after a negative exam is based mostly on expert opinion and on the timing of the adenoma–carcinoma sequence. Now, investigators in Manitoba, Canada, have conducted a retrospective analysis to estimate risk for developing colorectal cancer after a negative colonoscopy.

Using linked data from a population-based cancer registry and a medical-claims database, researchers identified 32,203 people who had negative screening colonoscopies and no prior history of colorectal cancer, colon resection, or inflammatory bowel disease (IBD). Follow-up after negative colonoscopy ranged from 6 months to 14 years. Compared with the general population, study subjects had significantly lower risk for colorectal cancer in the years following their negative colonoscopies. Standardized incidence ratios were 0.69 at 6 months, 0.55 at 5 years, and 0.28 at 10 years.

Comment: An editorialist notes that these data do not address the appropriate screening interval in higher-risk patients, such as those with IBD, or in patients who have polyps. However, in low-risk patients with negative exams, a screening interval of 10 years, and probably longer, is reasonable.

— Thomas L. Schwenk, MD

Published in Journal Watch General Medicine May 30, 2006

Citation(s):

Singh H et al. Risk of developing colorectal cancer following a negative colonoscopy examination: Evidence for a 10-year interval between colonoscopies. JAMA 2006 May 24/31; 295:2366-73.

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• Medline abstract (Free)

Church TR. Screening for colorectal cancer by colonoscopy: Adding to the evidence. JAMA 2006 May 24/31; 295:2411-2.

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• Medline abstract (Free)