Audit of the introduction of CT colonography for detection of colorectal carcinoma in a non-academic environment and its implications for the national bowel cancer screening programme

Aim

To compare the sensitivity of double-contrast barium enema (DCBE) with computed tomography colonography (CTC) to determine whether CTC is superior for the detection of colorectal cancer (CRC) locally, and to compare the results to those of a national barium enema audit.

Materials and methods

All patients undergoing diagnostic DCBE or CTC between January 2003 and December 2005 were identified from the picture archiving communication system (PACS). Patients with a confirmed diagnosis of CRC were identified from the local cancer registry. Patients who were not diagnosed as having CRC on imaging were assumed true negatives if they were not listed in the cancer registry by December 2007, giving a minimum of 2 years follow-up. DCBE and CTC reports of all patients with CRC were analysed, and cancer detection was considered to have occurred (positive test result) if the report stated the definite presence of CRC or possible CRC requiring further investigation.

Results

2520 DCBEs and 604 CTCs were included. Twenty-one of 33 patients with CRC were detected using DCBE (incidence 1.31%, sensitivity 63.7%). Thirty-two of 33 patients with CRC were -detected using CTC (incidence 5.46%, sensitivity 97.7%).

Conclusion

CTC is more sensitive for the detection of CRC, and its introduction in a district general hospital is justified. However, there has been a consequent decline in DCBE sensitivity, which, if reflected nationally, suggests CTC is the preferential screening test for CRC.