Baseline results from screening colonoscopy have been found to be highly predictive of 10-year outcomes, including identifying people at high risk of developing advanced neoplasia, according to a study published in Gastroenterology.

Data were collected from the Department of Veterans Affairs Cooperative Studies Program, which screened 3121 asymptomatic individuals aged 50 to 75 years who underwent a screening colonoscopy from 1994 through 1997 at 13 Veterans Affairs medical centers. The veterans were then followed for 10 years.

After colonoscopy, surveillance at 5 years was driven by a protocol of surveillance intervals determined by the participant’s most advanced lesion at the time of screening. Participants with no neoplasia at baseline were randomly assigned to either usual care or an examination at 5 years. Those with small adenomas (≤1 cm) were randomly assigned to usual care, examinations at 2 and 5 years, or an examination at 5 years only. Patients with advanced adenomas (excluding high-grade dysplasia) were assessed at 2 and 5 years; participants with high-grade dysplasia or colorectal cancer (CRC) received individual surveillance tailored by their physician.

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After completion of the initial 5-year surveillance protocol, participants were then followed for another 5 years (or until death), all while undergoing surveillance per usual care. The investigators reviewed all participants’ medical records for results from additional lower endoscopies, presence of advanced neoplasia (defined as advanced adenoma or CRC), and death.

The primary outcomes of advanced neoplasia or CRC alone were characterized at each colonoscopy on the basis of the most advanced neoplastic finding from the associated pathology results. Advanced neoplasia was defined as either an advanced adenoma (adenoma ≥10 mm or with villous histology or high-grade dysplasia) or invasive CRC. The timing of each surveillance colonoscopy was expressed as the number of days from the baseline exam.

Through 10 years of follow-up, there were 146 individuals among all baseline colonoscopy groups found to have at least 1 incident advanced neoplasia. The cumulative 10-year incidence of advanced neoplasia was highest among those with baseline CRC (43.7%), followed by those with baseline advanced adenoma (21.9%). The cumulative 10-year incidence of advanced neoplasia was 6.3% and 4.1% for patients with 1 to 2 small adenomas (<1 cm) and no neoplasia at baseline, respectively.

After adjusting for prior surveillance, the risk for advanced neoplasia at each subsequent examination was not significantly increased in veterans with 1 or 2 small adenomas at baseline compared with veterans with no baseline neoplasia.

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“Given the strong association of baseline findings with findings at subsequent examinations and the limited impact of known clinical factors, we hypothesize that genomic analysis may further clarify risk for CRC beyond the results of the baseline colonoscopy,” the authors concluded.


Lieberman D, Sullivan BA, Hauser ER, et al. Baseline colonoscopy findings associated with 10-year outcomes in a screening cohort undergoing colonoscopy surveillance. Gastroenterology. 2020;158(4):862-874.