A comparison of optical colonoscopy and CT colonography screening strategies in the detection and recovery of subcentimeter adenomas.

Objectives: Evidence has shown that computerized tomographic colonography (CTC) and optical colonoscopy (OC) can detect advanced adenomas at an equal rate; however, a comparison of the subcentimeter adenoma detection has not been performed. The objective of this study is to compare CTC and OC screening programs, with a focus on the detection and recovery of subcentimeter adenomas.

Methods: In all, 1,700 screening OC examinations in average-risk patients were compared with 1,307 CTC examinations in similar patients drawn from the same referral pool completed in 2006-2008. The detection rate for adenomas ≤ 5 mm, 6-9 mm, and <10 mm with advanced histology were compared.

Results: In the OC group, 23.2% of patients had at least one adenoma removed; in the CTC screening group, 5.9% of patients had at least one adenoma detected and removed, P<0.001. There were significantly more ≤ 5 mm adenomas (detection rate 0.22, 378/1,700) detected by OC than by CTC (detection rate 0.04, 56/1,307), P<0.001. There were significantly more adenomas 6-9 mm (detection rate 0.12, 204/1,700) detected by OC than by CTC (detection rate 0.05, 67/1,307), with 70 patients with polyps of unknown histology in CTC surveillance, P<0.001. The number of advanced lesions <10 mm detected by OC (15/1,700) compared with CTC (4/1,307) were not significantly different, P=0.06. In the OC group, 27.1% of patients had non-adenomatous polyps removed; in the CTC group, 4.1% of patients had non-adenomatous polyps removed, P<0.001.

Conclusions: (i) An OC screening program detects and recovers a significant four and a half fold greater number of non-advanced adenomas compared with a CTC screening program. (ii) The primary difference between screening with OC and CTC is the recovery and management of the subcentimeter adenoma.