Do surveillance intervals in patients with more than five adenomas at index colonoscopy be shorter than those in patients with three to four adenomas? A Korean Association for the Study of Intestinal Disease study

Abstract

BACKGROUND AND AIM: There is controversy about the surveillance interval after colonoscopy when 5-10 adenomas have been found on index colonoscopy. This study aimed to investigate the risk of colorectal neoplasm (CRN) according to the number of adenomas at index colonoscopy. METHODS: A retrospective, multicenter study was conducted at 10 university hospitals in Korea. We included 1394 patients with ≥3 adenomas at index colonoscopy. The risk of advanced CRN was compared according to the number of adenomas (intermediate risk group, 3-4 small adenomas or at least one ≥10mm, and high risk group, ≥5 small adenomas or ≥3 at least one ≥10mm). RESULTS: Overall, 164 (11.8%) developed an advanced CRN after a mean of 4.0years from baseline colonoscopy. The 3-year and 5-year risk of advanced CRN was 2.1% (95% CI 2.09-2.11) and 14.4% (95% CI 14.36-14.44) in intermediate risk group and 3.2% (95% CI 3.19-3.21) and 23.3% (95% CI 19.15-19.25) in high risk group (P=0.01). Having ≥5 adenomas (OR=1.57, 95% CI 1.11-2.23, P=0.01) detected at index colonoscopy was a significant risk factor for developing advanced CRN. CONCLUSIONS: Although risk of advanced CRN in patients with 5-10 adenomas was significantly higher than that in patients with 3-4 adenomas, the cumulative risk at 3years was low at 3.2%. Thus, we suggest that a 3-year surveillance interval might be appropriate for the patients with 5-10 adenomas, and further prospective studies are needed to investigate whether more intensive surveillance is needed in this group.