Risk of developing metachronous advanced colorectal neoplasia after resection of low-risk diminutive versus small adenomas.

BACKGROUND AND AIMS

Current postpolypectomy guidelines classify 1 to 2 diminutive (1-5 mm) nonadvanced adenomas (NAAs) and 1 to 2 small (6-9 mm) NAAs as low-risk adenomas and recommend the same surveillance interval for both lesions. We compared the risk of metachronous advanced colorectal neoplasia (ACRN) for both groups.

METHODS

We studied 8602 patients who underwent removal of ≥1 NAA and follow-up colonoscopic surveillance. Patients were categorized into 4 groups based on size and number of baseline NAAs: group 1, ≤2 diminutive NAAs (n = 6379); group 2, ≤2 small NAAs (n = 1672); group 3, ≥3 diminutive NAAs (n = 293); and group 4, ≥3 small NAAs (n = 258). Size was classified based on the largest NAA.

RESULTS

The 5-year cumulative incidence rates of metachronous ACRN in groups 1, 2, 3, and 4 were 2.7%, 5.1%, 10.7%, and 15.1%, respectively. Groups 2, 3, and 4 had a higher risk of metachronous ACRN than group 1. Compared with group 1, the adjusted hazard ratios for metachronous ACRN were 2.06 (95% confidence interval [CI], 1.46-2.91) for group 2, 2.75 (95% CI, 1.53-4.96) for group 3, and 4.49 (95% CI, 2.62-7.70) for group 4. However, the risk of metachronous ACRN was not significantly different between groups 3 and 4 (adjusted hazard ratio, 1.62; 95% CI, .76-3.44).

CONCLUSIONS

Among patients with ≤2 NAAs, patients with 1- to 5-mm NAAs had a lower risk of metachronous ACRN than those with 6- to 9-mm NAAs. The guidelines should consider extending surveillance intervals in patients with ≤2 diminutive NAAs.