Risk of advanced colorectal neoplasm by the proposed combined United States and United Kingdom risk stratification guidelines.

BACKGROUND AND AIMS

The U.K. guidelines for risk stratification after colon polypectomy differ from the U.S. guidelines in 2 ways: the U.K. guidelines consider ≥5 adenomas as high risk and do not consider histology (villous or high-grade dysplasia) in the assessment. Thus, we aimed to investigate the risk of advanced colorectal neoplasm (CRN) by categorized risk groups, considering both ≥5 adenomas and histology.

METHODS

A total of 2570 patients with ≥1 adenoma at index colonoscopy were included. The patients were divided into 6 groups: group 1, 1 to 2 non-advanced adenomas (non-AAs) ≥10 mm or high-grade dysplasia or villous adenoma; group 1A, 1 to 2 adenomas with ≥1 advanced adenoma (AA); group 2, 3 to 4 non-AAs; group 2A, 3 to 4 adenomas with ≥1 AA; group 3, ≥5 non-AAs; and group 3A, ≥5 adenomas with ≥1 AA. The risk of advanced CRN at 3 years was compared among the 6 groups.

RESULTS

Group 3A showed a higher risk of advanced CRN (9.6%) than group 3 (4.5%; P = .03) and group 1A (4.6%; P < .001). The risk of advanced CRN in group 3 (4.5%) showed no difference compared with group 1A (4.6%; P = .91) or group 2A (6.8%; P = .25). There was no difference between group 1 and group 2 in the risk of advanced CRN (1.7% vs 2.2%; P = .22). More than 1 AA at index colonoscopy was an independent risk factor for advanced CRN.

CONCLUSION

More-intensive surveillance than the 3-year interval for patients with ≥5 adenomas with ≥1 AA and less-intensive surveillance than the 3-year and 1-year intervals for those with 3 to 4 non-AAs and ≥5 non-AAs, respectively, might be suggested.