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Does CT colonography have a role in colorectal cancer screening?
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Yes, it could.
CT colonography is a valid option that may help improve screening rates.
Regardless of the technology, we don’t want to lose sight of the goal, which is to get patients screened. Whether it’s with colonography or colonoscopy or other methods, that’s really what physicians ought to be supporting.
There are definitely some advantages for some people, and it really should be looked at as another welcome screening option that patients and their physicians should consider. There are 70 million Americans who are eligible for colorectal cancer screening and probably only about half of them are following the screening guidelines, so we hope that CT colonography will provide an option that will increase screening compliance rates.
When considering CT colonography there are four important points to consider: performance, cost, safety and patient acceptance.
It’s been demonstrated that CT colonography’s performance is similar to colonoscopy, it’s about half the cost of colonoscopy if all charges are considered, it has a much lower complication rate compared to colonoscopy and it doesn’t require IV sedation, time off of work or an extra driver. We hope that these advantages will provide another option for patients so that those people who are currently not being screened will undergo colorectal cancer screening.
C. Daniel Johnson, MD, is Professor of Radiology at The Mayo Clinic, Arizona.
No, it shouldn’t.
Possibly in the future, but it is not ready for prime time in general GI practice.
First: The technology continues to evolve as it relates to sensitivity and specificity. The sensitivity has been very variable, and false-positive rates will drive up the number of duplicate tests payers will be responsible for.
Second: The positive predictive value is extremely low for CT, causing concern over the behavioral upset of patients who receive positive results from CT colonography and negative results from colonoscopy.
Third: Radiation is not an inconsequential exposure, particularly with CT scans, and we know there is a sizeable risk for the development of cancer as a result of this radiation exposure.
Fourth: One of the “values” is the detection of extracolonic findings. However, this adds incremental costs, both direct costs for pursuit of these evaluations and indirect costs that relate to patients.
Fifth: Like colonoscopy, all of the CT scans done in the United States are done with bowel preparation. In addition, if something is seen on CT colonography, the patient will need a colonoscopy and additional prep. The procedure may not be as noninvasive and pain-free as patients believe due to the air pumped into the rectum, and though there is no sedation, some patients may not want to remember any discomfort they may have experienced.
There is a continual push for technology to advance in CT scanning and there is a growing push for decreased radiation exposure with CT scanning. As it relates to colon screening at present day, the variability in the sensitivity and specificity data and the application outside of very high-selected centers of excellence seems premature.
David A. Johnson, MD, FACG, is Past President, American College of Gastroenterology and Professor of Medicine, Chief of GI at Eastern VA Medical School.