Diagnostic Accuracy of Computed Tomographic Colonography for the Detection of Advanced Neoplasia in Individuals at Increased Risk of Colorectal Cancer

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Abstract

Context

Computed tomographic (CT) colonography has been recognized as an alternative for colorectal cancer (CRC) screening in average-risk individuals, but less information is available on its performance in individuals at increased risk of CRC.

Objective

To assess the accuracy of CT colonography in detecting advanced colorectal neoplasia in asymptomatic individuals at increased risk of CRC using unblinded colonoscopy as the reference standard.

Design, Setting, and Participants

This was a multicenter, cross-sectional study. Individuals at increased risk of CRC due to either family history of advanced neoplasia in first-degree relatives, personal history of colorectal adenomas, or positive results from fecal occult blood tests (FOBTs) were recruited in 11 Italian centers and 1 Belgian center between December 2004 and May 2007. Each participant underwent CT colonography followed by colonoscopy on the same day.

Main Outcome Measures

Sensitivity and specificity of CT colonography in detecting individuals with advanced neoplasia (ie, advanced adenoma or CRC) 6 mm or larger.

Results

Of 1103 participants, 937 were included in the final analysis: 373 cases in the family-history group, 343 in the group with personal history of adenomas, and 221 in the FOBT-positive group. Overall, CT colonography identified 151 of 177 participants with advanced neoplasia 6 mm or larger (sensitivity, 85.3%; 95% confidence interval [CI], 79.0%-90.0%) and correctly classified results as negative for 667 of 760 participants without such lesions (specificity, 87.8%; 95% CI, 85.2%-90.0%). The positive and negative predictive values were 61.9% (95% CI, 55.4%-68.0%) and 96.3% (95% CI, 94.6%-97.5%), respectively; after group stratification, a significantly lower negative predictive value was found for the FOBT-positive group (84.9%; 95% CI, 76.2%-91.3%; P < .001).

Conclusions

In a group of persons at increased risk for CRC, CT colonography compared with colonoscopy resulted in a negative predictive value of 96.3% overall. When limited to FOBT-positive persons, the negative predictive value was 84.9%.

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