For patients with low or intermediate risk for colorectal cancer, the currently recommended colonoscopy screening interval of 10 years may potentially be extended, according to research published in Gastroenterology. Within 20 years of a negative index colonoscopy, the researchers found that advanced colorectal neoplasm prevalence remained low.

Study researchers set out to investigate the prevalence of advanced colorectal neoplasms after longer colonoscopy intervals. The study cohort included 2456 participants with neoplasms and at least 1 previous colonoscopy with negative results, as well as a cohort of 12,033 participants who underwent their first colonoscopy. Investigators assessed the time interval since last negative colonoscopy, both overall and in subgroups defined by sex, age, smoking history, family history, and body mass index (BMI). They also devised an integrative scoring system to assess colorectal cancer risk.

Of the colonoscopy-experienced patients, 72.3% had only 1, and 27.7% had 2 or more previous colonoscopies. The overall mean time interval since the last colonoscopy was 11.3 years (median, 10 years).

The prevalence of neoplasm was 5.5% within 20 years of a negative colonoscopy compared with 12.6% among patients without previous colonoscopy (adjusted prevalence ratio [aPR] 0.45; 95% CI, 0.37-0.53). The authors found little variation across 5-year time windows, with a 41% lower prevalence even more than 20 years after a negative colonoscopy, compared with those being screened for the first time.


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By subgroup, advanced colorectal neoplasm prevalence varied “only to a small extent.” When the investigators combined sex, age, BMI, smoking history, and family history into an algorithm, they got a high-risk subgroup with a 9% to 10% prevalence of advanced colorectal neoplasm. High BMI, per investigators, may require further investigation.

Study limitations include the use of information on previous colonoscopy collected via a self-reported questionnaire, which could have skewed results. Residual confounding was also possible due to the observational study design.

For patients who received a successful first screening, “currently recommended colonoscopy screening intervals could potentially be extended beyond ten years for the majority of people with low or intermediate [colorectal cancer] risk,” the researchers concluded.

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Reference

Heisser T, Guo F, Niedermaier T, Holleczek B, Hoffmeister M, Brenner H. Low risk of advanced neoplasms for up to 20 years after negative colonoscopy: Potential for personalized follow-up screening intervals [published online August 7, 2020]. Gastroenterology. doi: 10.1053/j.gastro.2020.08.003