Extracolonic findings on CT colonography increases yield of colorectal cancer screening

The purpose of this study is to evaluate the impact of extracolonic findings when screening is undertaken by CT colonography (CTC).

We performed a retrospective cohort study of patients completing a screening CTC from August 2003 to June 2006 at Walter Reed Army Medical Center. Extracolonic findings were categorized using a CTC reporting and data system that classifies findings as highly significant, likely significant, and insignificant. All final diagnoses, surgeries, malignancies, and costs of diagnostic radiology procedures were calculated for each category.

Of 2,277 patients (mean +/- SD age, 59 +/- 11 years; 60% white; 56% male) undergoing CTC, extracolonic findings were identified in 1,037 (46%) patients, with 787 (34.5%) insignificant and 240 (11.0%) significant findings. Evaluation of significant findings generated 280 radiology procedures and 19 surgeries over a mean follow-up time of 19 +/- 10 months. The total cost of the radiology studies was $113,179; the studies added approximately $50 extra per patient. Seven high-risk lesions were identified (six extracolonic malignancies and one large aortic aneurysm) in patients with significant findings. CTC also identified six intracolonic malignancies and three adenomas with high-grade dysplasia. When considering extracolonic findings, CTC increased the odds of identifying high-risk lesions by 78% (nine intracolonic lesions vs 16 intracolonic plus extracolonic lesions; p = 0.0156). Of the 16 intracolonic and extracolonic high-risk lesions, 11 (69%) underwent curative resection, and 5 of 11 (44.4%) were extracolonic.

CTC increased the odds of identifying high-risk lesions by 78%. CTC should be considered as an alternative to optical colonoscopy for colorectal cancer screening or as a onetime procedure to identify significant treatable intracolonic and extracolonic lesions.