Patients with polyps larger than 5 mm in computed tomography colonoscopy screening have high risk for advanced colonic neoplasia in Asia.

BACKGROUND & AIMS: Computed tomography colonography (CTC) is a recommended screening modality for colorectal cancer (CRC). It is not known whether polyps 6-9 mm based on CRC are likely to have advanced histologic features in Asian patients. We estimated the risk of advanced colonic neoplasia (ACN) from polyps <10 mm and the risk of ACN detection failure if patients with polyps <10 mm are not referred for colonoscopy.

METHODS

The study included 1457 subjects from the Asia-Pacific Working Group on CRC screening and the Hong Kong CRC screening program. Polyps and ACN found during colonoscopy examinations were classified by size and histology.

RESULTS

Of the subjects, 38.2% had polyps; 16.7% of these were ACN, 5.4% of ACN were ≤5 mm, and 24.7% of the ACN were 6-9 mm. Adopting the policy of reporting polyps found by CTC of <5 mm as normal and repeating CTC in patients with polyps of 6-9 mm, 5.4% of subjects with ACN, 4.5% of male subjects, and 11.5% of subjects with family history of CRC would be classified as normal. In referring patients with polyps of 6-9 mm for CTC surveillance, 20.4% of those with ACN, 22.4% of those that are male, and 23.1% of those with family histories of CRC would have polypectomies delayed by at least 3 years.

CONCLUSIONS

A substantial proportion of polyps <10 mm have advanced histologic features in Asia, so patients with a polyp of 6 mm or more at CTC should be offered colonoscopies with polypectomies, rather than CTC surveillance of polyps.