Inside Out

Our Review Summary

Colorectal cancer is the second leading cause of cancer deaths in the United States. Because of the silent nature of early disease, screening may allow earlier discovery of colorectal cancer at a time when treatment is most likely to make a difference in survival.  In addition to finding cancers early, screening may help prevent colorectal cancer through removal of polyps before they have a chance to develop into cancer.  In spite of good evidence that screening is effective at preventing deaths, rates of colorectal cancer screening lag behind that of other screening test such as mammography and PSA testing.

CT Colography, also known as "Virtual Colonoscopy" is one of the newer colorectal cancer screening options. Proponents claim that it is more convenient and acceptable to patients than colonoscopy, while others cite concerns about findings outside of the colon, radiation exposure, and the need for follow-up colonoscopy if something is found.

The story describes the cost of virtual colonoscopy compared to standard colonoscopy, although it isn’t clear that $1500 versus $800 is accurate in all setting and also does not include the fact that 20% will require a follow-up colonoscopy. The story also mentions the crucial issue of insurance coverage. While more insurance companies are starting to cover the procedure, many do not. The recent CMS decision not to cover it has been highly influential.

 The story adequately describes the evidence to support the procedure and cites conflicting conclusions from two different organizations – the American Cancer Society and the US Preventative Services Task Force (USPSTF). The story mentions standard colonoscopy as the alternative to virtual colonoscopy. The story could have also mentioned some of the other screening tests that are available, such as stool tests, sigmoidoscopy or barium enema.

The story does a good job of describing the potential harms of the procedure, including radiation exposure (250 times that of a chest x-ray), missing small or flat polyps, and incidental findings that might lead to unnecessary treatments. The story could have also emphasized that about 20% will require a follow-up colonoscopy because of suspicious findings.

The story could have been improved by quantifying the benefits of CT colography. While it does provide the frequency of incidental findings, it does not indicate what percentage of polyps are found relative to standard colonoscopy.