https://immattersacp.org/weekly/archives/2012/05/15/4.htm

Laxative-free CT colonography may be acceptable alternative for cancer screening

Colon cancer screening with laxative-free computed tomographic colonography offers a better experience for patients and may be an acceptable alternate method, a new study indicates.


Colon cancer screening with laxative-free computed tomographic colonography (CTC) offers a better experience for patients and may be an acceptable alternate method, a new study indicates.

Researchers performed a prospective test comparison of laxative-free CTC, which included electronic bowel cleansing and computer-aided detection, and optical colonoscopy in 605 adults 50 to 85 years of age (53% men, 47% women) who were at average to moderate risk for colon cancer. For electronic bowel cleansing, patients followed a low-fiber diet and ingested small amounts of contrast material to tag feces, which computer software then removed from the CTC images while maintaining the size and appearance of mucosal folds and polyps. Technicians performing the optical colonoscopies did not know the CTC results until colonoscope withdrawal, at which time reexamination could be done to resolve discrepant findings.

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The reference standard was unblinded optical colonoscopy. Outcome measures were per patient sensitivity and specificity of CTC and initial optical colonoscopy for detection of adenomas 10 mm or greater, 8 mm or greater, and 6 mm or greater. Sensitivity per lesion and survey data on patients' experience with the exam and with preparation were also examined. The results of the study, which was funded by GE Healthcare and the American Cancer Society, appear in the May 15 Annals of Internal Medicine.

Per patient sensitivity for adenomas 10 mm or larger was 0.91 (95% CI, 0.71 to 0.99) for CTC and 0.95 (95% CI, 0.77 to 1.00) for optical colonoscopy; specificity was 0.85 (95% CI, 0.82 to 0.88) and 0.89 (95% CI, 0.86 to 0.91), respectively. For adenomas 8 mm or larger and 6 mm or larger, respectively, CTC had a sensitivity of 0.70 (95% CI, 0.53 to 0.83) and 0.59 (95% CI, 0.47 to 0.70) while optical colonoscopy had a sensitivity of 0.88 (95% CI, 0.73 to 0.96) and 0.76 (95% CI, 0.64 to 0.85). Optical colonoscopy had a specificity of 0.91 at 8 mm or larger and 0.94 at 6 mm or larger versus 0.86 and 0.88, respectively, for CTC (P=0.02). Patients reported more comfort and less difficult exam prep for CTC compared with optical colonoscopy.

The authors acknowledged that only three people interpreted the CTC results and that the survey instrument used to assess patients' experience was not independently validated, among other limitations. However, they concluded that CTC offered a better patient experience and accurately detected larger adenomas (10 mm or larger), although it was not as accurate in detecting smaller lesions. “Our results suggest a role for CTC as an alternate screening method to [optical colonoscopy] with which participants would experience improved preparation and examination comfort—factors that could contribute positively to overall screening participation,” the authors wrote.