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CT colonography identified almost 80% more high-risk lesions compared with optical screening by adding extracolonic findings, a review of more than 2,000 cases showed.

CT showed extracolonic findings in almost half of the cases, a fourth of which were considered significant. The findings led to 280 radiology procedures and 19 surgeries, adding about $50 per patient.

"CT colonography (CTC) not only identifies colorectal cancer [CRC] but also doubles the yield of identifying significant early extracolonic lesions, resulting in lives saved," Ganesh Veerappan, MD, of Walter Reed Army Medical Center in Washington, and co-authors reported in the September issue of the American Journal of Roentgenology.

"These results represent a compelling reason to consider CTC either as an alternative to optical colonoscopy CRC screening or as a one-time procedure to identify significant treatable intracolonic and extracolonic lesions."

CT colonography, or virtual colonoscopy, does not replace a CT scan of the abdomen and pelvis for detecting significant extracolonic lesions, the authors emphasized. Because of its lack of contrast material and low radiation dose, CT colonography's sensitivity for detecting extracolonic lesions is lower than that of a conventional CT scan.

Because CT colonography enables examination of the entire abdomen and pelvis, the imaging modality shows extracolonic findings in a substantial proportion of patients. Prior studies have suggested that these extracolonic findings are clinically significant in 10% to 23% of cases, the authors wrote in their introduction.

The clinical and economic impact of CT colonography's extracolonic findings had not been studied carefully, and that was the objective of Veerappan and co-authors.

They retrospectively reviewed records of 2,277 patients who had screening CT colonography at Walter Reed from 2003 to 2006. A CT colonography reporting and data system was used to classify findings as highly significant, likely significant, or insignificant.

Screening CT colonography showed extracolonic findings in 1,037 (46%) of patients. The findings were considered insignificant (E2 by the reporting system) in 787 cases and significant in 240 (E3-4).

During a mean follow-up of 19 months, evaluation of significant findings led to 280 radiology procedures and 19 surgeries, resulting in a total cost of $113,179, or about $50 per patient screened.

Screening CT colonography identified six intracolonic malignancies and three adenomas with high-grade dysplasia. Additionally, the imaging studies identified six extracolonic malignancies and one abdominal aortic aneurysm.

CT colonography detected 16 high-risk lesions, whereas nine would have been identified by optical colonoscopy, resulting in a 78% increase in the yield of high-risk lesions. Eleven of the 16 lesions were treated by curative surgery, and five of the 11 lesions were extracolonic.

"Of 2,277 patients undergoing CT colonography (CTC) for CRC screening, extracolonic findings doubled the yield of cancer identification from six to 12," the authors noted. "This is a clear advantage of this new technology that needs to be weighed into future recommendations concerning CRC screening."

Limitations of the study included its retrospective design and inability to follow patients who may have been treated outside of the military health system.

Source: American Journal of Roentgenology