Kolorektal kanser tespitinde CTC (İng)


CTC vs. Colonoscopy: Tie Score

Detection of colorectal cancer or large polyps was the same with computed tomographic colonography or colonoscopy in symptomatic patients, but CTC resulted in more follow-up examinations.

Increasing evidence suggests that computed tomographic colonography (CTC) has high sensitivity for detecting colorectal cancer — comparable to optical colonoscopy for polyps 10 mm but inferior for polyps <10mm (JW Gastroenterol Sep 17 2008 and JW Gastroenterol May 18 2012. The first randomized, controlled trial to directly compare laxative-free CTC and colonoscopy in a screening population found better participation for CTC but higher yield of advanced neoplasia for colonoscopy in actual participants (Lancet Oncol 2012 Jan; 13:55). Now, investigators in the U.K. have conducted a second randomized trial of CTC versus colonoscopy to compare the frequency of additional colonic investigation required in patients with colorectal symptoms.

Of all patients (mean age, 68), 1072 underwent colonoscopy and 538 underwent CTC. Patients in the CTC group were >3 times more likely than patients in the colonoscopy group to undergo additional colonic investigation (30.0% vs. 8.2%; relative risk, 3.65; P<0.0001). This increased likelihood was stronger in men (relative risk, 6.39) than in women (RR, 2.41) but was significant within each subgroup. In the colonoscopy group, the overall cecal intubation rate was 89%, and >80% of patients who underwent additional investigation did so for incomplete examination. Half of the patients in the CTC group who received an additional evaluation had colorectal cancer or a polyp 10 mm, and approximately one third were referred to colonoscopy for polyps <1 cm. CTC and colonoscopy groups did not differ in detection rates for colorectal cancer (5.6% and 5.7%) or for polyps 10 mm (5.2% and 6.3%). During 3 years of subsequent follow-up, only 1 new cancer was diagnosed in the CTC group (of 29 total) and none in the colonoscopy group (of 55 total).

Comment: All of the computed tomographic colonographies were performed by “gastrointestinal radiologists.” Colonoscopies were performed by gastroenterologists or colorectal surgeons (numbers of each not specified). The authors express concern that too many patients randomized for CTC underwent colonoscopy for lesions <10 mm in size, thereby diminishing the cost-effectiveness of CTC. The same authors previously found that patients preferred CTC to colonoscopy (Radiology 2012; 263:723). Because that study was performed in the U.K., where colonoscopy is commonly performed with only minimal to moderate sedation, our ability to generalize those results to the U.S. is uncertain. In addition, the 89% cecal intubation rate during colonoscopy in this study would fall below current quality standards recommended in the U.S. Moreover, the current findings do not include overall adenoma detection rates and histology of colorectal polyps, which makes it difficult to assess whether the 5.7% prevalence of polyps 10 mm in a symptomatic population of a mean age of 68 represents adequate detection during colonoscopy. To me, it seems low. Conducting a similar trial in the U.S. — one that employed endoscopists with proven detection capabilities and U.S.–style sedation for colonoscopy — would be beneficial.

— Douglas K. Rex, MD

Published in Journal Watch Gastroenterology March 8, 2013