Indeterminate but Likely Unimportant Extracolonic Findings at Screening CT Colonography (C-RADS Category E3): Incidence and Outcomes Data From a Clinical Screening Program.

Abstract

The purpose of this study was to analyze the incidence and outcomes of unsuspected indeterminate but likely unimportant extracolonic findings (CT Colonography Reporting and Data System [C-RADS] category E3) at screening CT colonography (CTC). Over 99 months (April 2004 through June 2012), 7952 consecutive adults without symptoms of colorectal cancer (4277 women, 3675 men; mean age ± SD, 56.7 ± 7.3 years) underwent first-time screening CTC. Findings prospectively placed into C-RADS category E3 were retrospectively reviewed, including follow-up (range, 2-10 years) and ultimate clinical outcome. Unsuspected C-RADS category E3 extracolonic findings were detected in 9.1% (725/7952) of our patient population. A total of 751 category E3 findings were detected among these 725 patients; 25 patients had multiple findings. Commonly involved organ systems included gynecologic (24.4%, 183/751), genitourinary (20.9%, 157/751), lung (20.6%, 155/751), and gastrointestinal (16.1%, 121/751). Consideration for further imaging, if clinically warranted, was suggested in 83.8% (608/725). Sixty-five patients were lost to follow-up. Conditions requiring treatment or surveillance were ultimately diagnosed in 8.3% (55/660), including eight malignant neoplasms. In the remaining 605 patients, 25 (4.1%) underwent invasive biopsy or surgery to prove benignity (including 18 complex adnexal masses), and 278 (46.0%) received additional imaging follow-up. Indeterminate but likely unimportant extracolonic findings (C-RADS category E3) occurred in less than 10% of adults without symptoms of colorectal cancer who underwent screening CTC. Over 90% of these findings ultimately proved to be clinically insignificant, with fewer than 5% requiring an invasive procedure to prove benign disease, the majority of which (> 70%) were complex adnexal lesions in women.