CT Colonography to exclude colorectal cancer in symptomatic patients

CT Colonography (CTC) is being increasingly used for the radiological evaluation of colorectal symptoms. Aim of this study was to assess the role of CTC in excluding a colorectal cancer (CRC) in older symptomatic patients.

1,359 CTC studies performed between March 2002 and December 2007 were analysed retrospectively. Gold standard was an endoscopic examination within 1 year and/or clinical, endoscopic and/or radiological follow-up until the time of data analysis. Patients not diagnosed as having a CRC on CTC were assumed as true-negatives if the gold standard was negative and did not feature on the regional cancer registry (at least 18 months post-CTC). Sensitivity, specificity, positive and negative predictive values were calculated for detection of colorectal cancer.

After exclusions, 1,177 CTC studies were included. These were undertaken in 463 men and 714 women. Median age of patients undergoing CTC was 71 (range, 27-96) years. 59 invasive CRC were detected. Median follow-up was 34.5 (range 18-84) months. Three small colorectal cancers were missed. Sensitivity and negative predictive value for CRC were 94.9% (95% CI:84.9%-98.7%) and 99.7% (95% CI:99.1%-99.9%) respectively.

CTC has a high sensitivity and negative predictive value in excluding a CRC in patients with colorectal symptoms.