Is computed tomographic colonography as accurate as optical colonoscopy for detection of advanced neoplasia?

As the technology has improved, computed tomographic colonography (CTC) has become a viable and potentially less costly initial screening tool for colon cancer. Questions remain about the best way to handle intermediate-sized lesions (6 mm to 9 mm) and the optimal screening interval. Also, flexible sigmoidoscopy remains a good option for younger patients (Gastroenterology 2007;132:2304-12). (LOE = 2c)

Kim DH, Pickhardt PJ, Taylor AJ, et al. CT colonography versus colonoscopy for the detection of advanced neoplasia. N Engl J Med 2007;357(14):1403-1412.  [PMID:17914041]

Cohort (retrospective)

Unknown/not stated

Outpatient (specialty)

In this nonrandomized parallel groups study the authors compared outcomes for patients referred for either CTC or traditional optical colonoscopy (OC). We only have limited demographic data for the groups, but their ages, gender ratios, and the percentage with symptoms (~ 2.1%) were similar. Patients referred for OC were more likely to have a family history of colorectal cancer (8.4% vs 5.1%; P < .001). CTC typically involved both a bowel cleansing with a single 45-ml dose of sodium phosphate with oral barium and diatrizoate contrast; no sedation was required. OC used 4 liters of polyethylene glycol or two 45-ml doses of sodium phosphate, and required sedation with midazolam and fentanyl. In the CTC group, 7.9% of patients were referred for same day OC for any polyps 6 mm in diameter or larger. Patients with only 1 or two 6- to 9-mm polyps were given the option of CTC surveillance instead of biopsy. Although there were more total polyps removed in the OC group than in the CTC group (2434 vs 561; P < .001), there was no difference in the number of advanced adenomas. In fact, more invasive carcinomas were seen in the CTC group (14 vs 4; P = .02). Although CTC does not reliably detect polyps smaller than 5 mm in diameter, only 4 of 2006 such polyps in the OC group were advanced lesions. A disadvantage of OC was a higher complication rate: 7 perforations in the OC group (including 4 that required surgical repair) versus none in the CTC group.