Low rates of cancer or high-grade dysplasia in colorectal polyps collected from computed tomography colonography screening.

Background & Aims: In patients with polyps detected at computed tomography colonography (CTC) screening, management decisions are influenced by the likelihood of important polyp histology. We assess the rates of cancer and high-grade dysplasia among patients found to have small (6-9 mm) and large (>or=10 mm) colorectal polyps at CTC.

Methods: We reviewed results from 5124 consecutive adults (mean age, 56.9 y; 2792 women) who received CTC screening at 1 institution over a 52-month period. All nondiminutive lesions confirmed at subsequent colonoscopy were grouped by size and histology features. Rates of cancer and high-grade dysplasia were calculated for various sizes. Adenomas were classified as advanced if they were 10 mm or greater and/or contained high-grade dysplasia or a prominent villous component.

Results: A total of 755 polyps 6 mm or greater were identified during colonoscopy examinations in 479 patients. The rate of malignancy, according to polyp size, was 0% (0 of 464) for polyps 6 to 9 mm, 0.9% (2 of 216) for polyps 10 to 19 mm, 6.1% (2 of 33) for polyps 20 to 29 mm, and 38.1% (16 of 42) for polyps 30 mm or greater. High-grade dysplasia was observed in 0.4% (2 of 464) of 6- to 9-mm polyps and 7.9% (23 of 291) of lesions 10 mm or greater. A prominent villous component was seen in 3.4% (16 of 464) of 6- to 9-mm polyps. The overall rate of advanced histology in small polyps was 3.9% (18 of 464).

Conclusions: Small (6-9 mm) polyps rarely contained high-grade dysplasia (0.4%); none was malignant. The malignancy rate for large (1-2 cm) colorectal polyps was less than 1%. These findings indicate the potential for less aggressive management of lesions detected by CTC.