Background: Suggested intervals for postpolypectomy surveillance colonoscopy are currently based on the adenoma findings from the most recent examination.
Objective: To determine the risk for clinically significant adenoma recurrence on the basis of the results of 2 previous colonoscopies.
Design: Prospective cohort study.
Setting: Academic and private centers in North America.
Patients: Participants in an adenoma chemoprevention trial in which all participants had 1 or more adenoma found on complete colonoscopy at entry. For this analysis, only participants whose qualifying adenoma was their first were included. All participants then underwent second and third study colonoscopies at roughly 3-year intervals.
Measurements: Proportion of patients with high-risk findings at the third study colonoscopy--either at least 1 advanced (> or = 1 cm or advanced histology) adenoma or multiple (> or = 3) adenomas.
Results: Fifty-eight of 564 participants (10.3%) had high-risk findings at the third study examination. If the second examination showed high-risk findings, then results from the first examination added no significant information about the probability of high-risk findings on the third examination (18.2% for high-risk findings on the first examination vs. 20.0% for low-risk findings on the first examination; P = 0.78). If the second examination showed no adenomas, then the results from the first examination added significant information about the probability of high-risk findings on the third examination (12.3% if the first examination had high-risk findings vs. 4.9% if the first examination had low-risk findings; P = 0.015).
Limitation: This observational study cannot specifically examine adenoma recurrence risk at intervals suggested for patients with low-risk adenomas (for example, 5 years vs. 10 years).
Conclusion: Information from 2 previous examinations may help identify low-risk populations that benefit little from intense surveillance. Surveillance guidelines might be tailored in selected patients to use information from 2 previous examinations, not just the most recent one.
Primary funding source: National Institutes of Health.