Studies Support CT Colonography as First-Tier Alternative to Colonoscopy

The case for the use of computed tomographic (CT) colonography, also known as the virtual colonoscopy, as an alternative to the standard colonoscopy continues to gain support through continuing studies. The test involves an examination of the colon and rectum using pictures obtained using a CT scanner for the purpose of detecting tumors and precancerous lesions. The latest of several studies focusing on the success rate of the procedure has deemed it to be almost as dependable as the standard colonoscopy.

The traditional colonoscopy involves the use of a tiny camera that is threaded through the rectum. The device includes a tiny pair of clippers used to remove suspicious-looking growths, called polyps, to determine whether or not they could become cancerous. Although the argument of many experts who have not yet embraced the CT colonography remains that colon cancer is more successfully detected at earlier and more treatable stages using colonoscopy, according to Italian researchers, the use of the CT Colonography may be a first-tier option for many.

Dr Daniele Regge of the Institute for Cancer Research and Treatment in Turin, Italy, said that the virtual procedure could offer an alternative for those who are either embarrassed by or afraid to undergo a standard colonoscopy and that the procedure may encourage them to be examined.

The study, published in the Journal of the American Medical Association, involved a final total of 937 participants. During the final analysis, 373 were grouped for family history, while 343 were grouped for personal history of adenomas (benign tumors), and 221 were grouped for testing positive from fecal occult blood testing. Both CT colonography and colonoscopy were used on the study participants.

The CT colonography was successful in detection of 151 of 177 participants having advanced neoplasia (tumor formation) 6 mm or larger, as well as in correctly determining negative results for 667 of 760 participants who had no lesions. According to the researchers, “CT colonography detected 39 of 41 participants with cancer, including all 3 with diameters of 6 to 9 mm.” They concluded that the findings “suggest a potentially effective use of CT colonography as an alternative to colonoscopy for screening individuals with family history of advanced colorectal neoplasia.”

In addition, the team noted, “Computed tomographic colonography has been shown to be better accepted than colonoscopy and has a negligible risk of serious adverse events; thus, it may help increase the low adherence reported for individuals who are candidates for screening, which is the main negative factor affecting its efficacy in reducing mortality from CRC.”

The results of the study support another recent analysis performed by Dr. C. D. Johnson of Scottsdale, Arizona in which more than 2,500 participants underwent both CT colonography and a colonoscopy followed by a full evaluation of the results of the tests. When compared to colonoscopy, CT colonography successfully detected 90 percent of the pre-cancerous polyps of 9.0 mm or more in diameter but only 78 percent of pre-cancerous polyps of 6.0 mm to 9.0 mm in size, compared to 100 percent detection by colonoscopy.

One downside of using CT colonography is that the technology is known to have about a 14 percent false-positive rate. This leads to the need for those patients who receive them to undergo an unnecessary colonoscopy. However, erring on the safe side is the far better choice. In fact, the CT scans allow more areas of the body to be viewed than does the colonoscopy, allowing for the detection of other problems serious enough to lead to further testing or urgent care.  In Johnson’s study, a total of 16 percent of the patients we found to have these types of problems and were therefore able to take action.

Although Colonoscopies and CT colonography are both life-saving tools used by medical science, neither test can detect all the dangers that lurk within the rectum and colon. Neither test encompasses the precision to detect much more dangerous nonpolypoid lesions as they are flat or depressed and similar in color to healthy tissue. These lesions are 10 times as likely to be cancerous as the easy-to-detect polyps. However, a special technique that uses an indigo spray to highlight the lesions can be used with the colonoscopy to better spot the lesions.