Diagnostic Accuracy of Laxative-Free Computed Tomographic Colonography for Detection of Adenomatous Polyps in Asymptomatic Adults

Abstract

Computed tomographic colonography was accurate in detecting adenomas 10 mm or larger but less so for smaller lesions. Patient experience was better with laxative-free CTC. These results suggest a possible role for laxative-free CTC as an alternate screening method.

Colonoscopy: The Current King of the Hill in the USA

“…These lesions are not well seen at CT colonography 44,45 , and CT colonography trials never report serrated lesions as a separate outcome. Absence of blood vessels on the surface of serrated lesions has long led to suspicion that guaiac based FOBT and FIT could not detect them, which proved completely true when finally tested 46 .…”

Colorectal cancer screening

“…(23) Moreover, data from computed tomography (CT) colonography studies has enabled the sensitivity of colonoscopy to be estimated so that the results can be applied to community practice. (24)(25)(26)(27) Compared with CT colonography or colonoscopy with CT colonography (e.g. segmental unblinding), the sensitivity of colonoscopy is 89%-98% for detecting adenomas ≥ 10 mm and 75%-93% for adenomas ≥ 6 mm.…”

Alternatives to colonoscopy for population-wide colorectal cancer screening

“…40,41 Furthermore, Abbreviations: CI = confidence interval; CRC = colorectal cancer; gFOBT = guaiac faecal occult blood testing; iFOBT = immunohistochemical faecal occult blood testing; N/A = not available; NNScope = the number of colonoscopies needed to diagnose an advanced adenoma after screening revealed a likely significant lesion; NNScreen = the number of average-risk individuals needed to recruit in a screening programme to detect one advanced adenoma; PPV = positive predictive value * gFOBT1 = Hemoccult II; gFOBT2 = Hemoccult Sensa; iFOBT1 = OC-Light; iFOBT2 = OC-SENSOR; iFOBT3 = RIDASCREEN Haemoglobin; iFOBT4 = RIDASCREEN Haemo-/Haptoglobin Complex; iFOBT5 = FOB-Gold; iFOBT6 = Magstream; iFOBT7 = FlexSure OBT † Studied distal colorectal cancer only ‡ Cut-off value at 100 ng/mL § Cut-off value at 75 ng/mL ∥ Sensitivity ratio (ratio of true positives with iFOBT to that with gFOBT) was estimated as sensitivities could not be directly calculated assessment of the extra-colonic organs can be performed at the same time. 42 A lower volume bowel preparation may be used 43 and the radiation risk is negligible. 41 Its main disadvantage is that biopsy is not possible, and the patient may require a second procedure with another bowel preparation, thus imposing additional costs and discomfort to the patient.…”

“…53 The use of 'low-prep' or laxative-free CTC is being further investigated. 43 The CTC can detect asymptomatic polyps and has the potential to prevent them from progressing to advanced adenoma and CRC. These polyps may not be detected by gFOBT or iFOBT until they result in microscopic haemorrhage in the lower GI tract.…”