Size and multiplicity are risk factors for the recurrence of high-risk adenomas in a colorectal cancer screening cohort

Introduction A proportion of patients develop recurring adenomas within a given follow-up interval, and little is known of the determinants of high-risk adenoma recurrence.

Aims To identify the number of patients harboring high-risk adenomas at follow-up when high-risk adenomas were present at baseline colonoscopy, and to examine possible risk factors for developing high-risk lesions within a screening or surveillance interval.

Methods Of 372,546 colonoscopies as part of a national screening quality program from 01/2007-04/2021, two cohorts were evaluated: the entire screening cohort, and patients presenting with high-risk adenomas on index colonoscopy. High-risk adenomas were defined as having at least one adenoma ≥ 10mm size, ≥ 5 adenomas, any serrated polyp ≥10mm with or without dysplasia or at least one lesion with high-grade dysplasia.

Results In the entire cohort, 51 % were female (median age 59 years). Of 10,929 patients with at least one follow-up visit, 1,352 (12.3 %) patients harbored high-risk adenomas at index and converted to a low-risk setting on their second visit. High-risk adenomas at index and follow-up were found in 195 individuals (1.7 %). Patients having high-risk adenomas were significantly more likely to present with high-risk lesions on follow-up colonoscopy (RR 3.15, CI 2.68-3.71). No significant difference in sex, age, bowel preparation score, dysplasia or adenoma detection rate (ADR) was identified between patients with recurrent high-risk adenomas compared to high-risk adenoma patients that had no high-risk adenoma on follow up (mean ADR 27.42 vs 27.44). On multivariate analysis, adenoma count and polyp size were identified to be independent predictors of recurrence of high-risk adenomas in this subgroup (HR 1.13, CI 1.08-1.17 and HR 1.17, CI 1.11-1.22). For the entire cohort, age, male sex, polyp count (HR 1.06, CI 1.05-1.07) and polyps ≥ 10mm (HR 5.51, CI 4.72-6.43) on index colonoscopy were independent predictors of recurrence of high-risk adenomas.

Interpretation This study highlights the importance of polyp count and size in the screening cohort and for patients presenting with high-risk adenomas as determinants of recurrence. The ADR does not seem to impact recurrence of high-risk adenomas.

Publication History

Article published online:
07 September 2021