CT Colonography Data Released
Complete Colonoscopy Still the Best Screening Test

The long awaited ACRIN Trial on CT colonography was released in the September 18, 2008 issue of the New England Journal of Medicine. While all of us on the front lines battling colorectal cancer welcome effective and clinically proven new tools, the evidence must be closely evaluated, and patients need to recognize that CT colonography is not without significant potential risks in its own right.
Screening by CT colonography for patients who would otherwise forego preventive screening clearly improves the likelihood of early detection. However, substituting CTC for complete colonoscopy creates the unfortunate potential for a sizeable miss rate or significant delay in detection of high risk pre-cancerous lesions. Delay could be dangerous or deadly.

Complete Colonoscopy is the Preferred Screening Strategy
Because of its excellent sensitivity in detecting polyps and its potential for removing them and breaking the sequence of polyp to cancer in a single diagnostic and therapeutic intervention, complete colonoscopy is one of the most powerful preventive tools in clinical medicine.

ACG Sees a Significant Potential Downside to CTC
Many patients who have polyps detected by CT colonography will still have to undergo complete colonoscopy; more than 17% in this study would have been referred and other studies have shown higher rates.

Radiation Risk a Concern
With a proposed screening schedule of five years or less for CTC, depending upon the findings, the cancer risks from the CTC test itself are not insignificant. Although it is a challenge to define precise risk estimates related to low doses of radiation exposure, the ionizing radiation exposure from a single abdominal or chest CT may be associated with elevated risk for DNA damage and cancer formation.

Patient Acceptability
In light of the underutilization of proven lifesaving colorectal cancer screening tests, the issue of patient acceptability is essential.
Patients need to understand that CT colonography does not represent a painless or risk-free procedure, nor does it eliminate the need for bowel cleansing which patients report as a barrier to screening. There is also evidence that due to the insertion of a tube in the rectum and insufflation of the abdomen with air or gas, the patients, who are not sedated and awake, tend to feel discomfort.

Role of the Clinical Gastroenterologist
Nobody in medicine understands the colon better than a gastroenterologist. It is critical that insurance companies and policymakers secure the ability for gastroenterologists to include appropriate tests of all kinds into their practices as the science proves their effectiveness. ACG will continue to fight for your interests.

Metro Atlanta Gastroenterology, LLC
(404) 255-4333 • 5669 Peachtree Dunwoody Road • Suite 210 • Atlanta, GA 30342