CT Colonography (CTC)
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CT Colonography (CTC)

AGA Clarifies Position on CT Colonography to BlueCross BlueShield of Delaware

Thank you to AGA members who notified AGA about BlueCross BlueShield (BCBS) of DE pilot study on CT Colonography (CTC). In a letter to BCBS network providers last month, BCBS incorrectly stated that the AGA and American Cancer Society (ACS) have endorsed CTC has a first-line colon cancer screening test. This is not the case. Recent guidelines from the ACS, AGA and other groups do not endorse any test as "first line." While the AGA supports CTC as a screening option, colonoscopy is the definitive test for colorectal cancer screening and prevention.

For more information on the AGA position, read the following letter to Paul A. Kaplan, MD, chief medical officer of BCBS of Delaware.

To flag other payor issues to the AGA, e-mail payorissues@gastro.org.

October 9, 2008

Paul A. Kaplan, MD
Chief Medical Officer
Blue Cross Blue Shield of Delaware
P.O. Box 1991
Wilmington, DE 19899-1991

Dear Dr. Kaplan,

The American Gastroenterological Association (AGA) and the AGA Institute comprise the largest society of gastroenterologists, representing more than 16,000 physicians and scientists who are involved in research, clinical practice and education on disorders of the digestive system.

On behalf of our members and their patients, I am writing to clarify an inaccuracy in your September 2008 letter to members regarding the Blue Cross Blue Shield of Delaware's Pilot Study with Colon Health Centers to provide CT colonography. The AGA does not endorse CT colonography as a first-line colon cancer screening test.

While AGA supports CT colonography as a screening option, colonoscopy is the definitive test for colorectal cancer screening and prevention. Colonoscopy is the only test that can both detect cancer at an early curable stage and prevent cancer by removing pre-cancerous polyps. At this time, while CT colonography may be another technology for colorectal cancer screening, many questions about CT colonography remain to be answered. I have enclosed for your review the AGA’s discussion of these outstanding questions in attached press releases from March 5 and Sept. 18, 2008.

I suspect the misstatement in your letter comes from an inaccurate interpretation of the 2008 colorectal cancer screening guidelines issued by the American Cancer Society and other groups.

The AGA and ACS point out that the guidelines do not endorse any test as "first line." Rather, the guideline authors provide a list of testing options, including CT colonography. The authors note the "strong opinion...that colon cancer prevention should be the primary goal of screening,” and recommend that tests that have a high likelihood of detecting both early cancer and adenomatous polyps should be encouraged if resources are available and patients are willing to undergo an invasive test. These tests include the endoscopic and radiologic structural exams. While these tests are all options, each has unique characteristics -- thus it would be inaccurate to say that one test is "on par" with another. Both providers and patients should understand the requirements and limitations of each form of testing, and make a decision on which test to use based on their own particular circumstances.

The AGA requests that BCBS of Delaware sends a revised letter correcting the misstatement to every physician and member who received the September 2008 letter.

Sincerely,

Robert Sandler, MD, MPH, AGAF
President, AGA Institute

Cc: Matthew Denn, Insurance Commissioner, State of Delaware
Durado Brooks, MD, MPH, Director, Colorectal and Prostate Cancers, American Cancer Society
Robert Smith, PhD, Director, Cancer Screening, American Cancer Society

Recent AGA statements on CT colonography.
More information on our position is available at www.gastro.org/ctc.

PRESS STATEMENT: September 2008

Data Support CT Colonography as Viable Colorectal Cancer Screening Option
Colonoscopy Still the Definitive Test for Colorectal Cancer Screening and Prevention

Death from colorectal cancer is highly preventable with effective screening and early detection. Many screening options are available, each with advantages and disadvantages, but half of eligible patients still do not participate in colorectal cancer screening. For that reason, a goal of the AGA Institute is to increase colorectal cancer screening rates and improve public health.
The AGA Institute considers colonoscopy the definitive test for colorectal cancer screening and prevention. Colonoscopy is the only test that can both detect cancer at an early curable stage and prevent cancer by removing pre-cancerous polyps. Data published in the Sept. 18, 2008, issue of the New England Journal of Medicine suggests that computed tomographic (CT) colonography may be another acceptable technology for colorectal cancer screening.

The availability of CT colonography could increase screening rates in eligible patients (i.e. asymptomatic patients over the age of 50) who have not participated in other colorectal cancer screening procedures. However, a number of important questions need to be addressed:

  • Does CT colonography find all possible cancers? These study results showed that CT colonography detected 90 percent of large polyps (>10 mm), a rate on par with traditional colonoscopy. However, CT colonography was less sensitive for small polyps (5 mm to 9 mm), with detection rates as low as 65 percent (5 mm). These small polyps were not removed. It is not clear that leaving small polyps is safe; there are no long-term, adequately controlled studies on the subject. The need to define the natural history and biological significance of small polyps is central to refining colorectal cancer screening, irrespective of modality. This study did not investigate diminutive polyps (<5 mm) and the ability of CT colonography to detect flat lesions remains unanswered.
  • Will CT colonography be accurate in all settings? Study investigators were highly trained in CT colonography, perhaps increasing the accuracy rate of this test. Standardized, rigorous training and proper technique are essential to ensuring that CT colonography achieves appropriate sensitivity, specificity and performance.
  • Do patients understand the pros and cons of the available colorectal cancer screening tests?
    Despite the perception that CT colonography is less invasive than traditional colonoscopy, it requires similar bowel preparation as for a colonoscopy. Patients need to understand that a prep is required for CT colonography, and if a polyp is found, it must be removed through a subsequent colonoscopy. Only colonoscopy can prevent colorectal cancer, by removing pre-cancerous polyps.

    Patients also need to understand that for most people colorectal cancer screening is not a one-time event and that interval examinations are recommended. According to a study by Thomas F. Imperiale et al.ii, published in the same issue of NEJM, a screening interval of five years or longer is appropriate in patients with a normal colonoscopic exam. Because small (< 5 mm) polyps are not typically reported on CT colonography, a negative exam on CT may not be equivalent to a negative colonoscopy. The optimal interval between CT colonography examinations has yet to be defined.
  • What are the radiation risks? The potential for harm from radiation is difficult to assess given the uncertainty of true risks from low levels of radiation exposure. However, the ionizing radiation exposure from a single abdominal or chest CT may be associated with elevated risk for DNA damage and cancer formation. The rate of radiation exposure with CT colonography may depend on the machine used and the type of CT colonography (2-D versus 3-D imaging) performed; therefore the methodology for screening must be standardized. For more information about the risk of radiation exposure, read the NIH fact sheet, “What We Know About Radiation.”

Guided by the principle that gastroenterologists are ideally suited to manage patients with gastrointestinal disorders and that they should be able to utilize any technology that can enable them to provide better patient care, the AGA Institute has taken a leadership role with technologies such as CT colonography. With the best interest of patients in mind, the AGA has monitored this technology, created training standards and will continue to educate those gastroenterologists who wish to provide this procedure to patients.

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PRESS RELEASE: March 2008

AGA Supports New Guidelines Favoring Tests That Prevent Colorectal Cancer

Bethesda, MD (March 5, 2008) – New consensus colorectal cancer guidelines released today state for the first time that the primary goal of colorectal cancer screening is cancer prevention. Previous guidelines have given equal weight to tests for detecting cancer and preventing cancer. By removing polyps from the large bowel, colonoscopy is the only screening test that also prevents colorectal cancer.

“Colorectal cancer prevention should be the primary goal of screening,” said Nicholas LaRusso, MD, AGAF, president, American Gastroenterological Association (AGA) Institute. “Detection and removal of precancerous lesions is essential to improve the health of Americans.”

The guidelines, which represent the most current scientific evidence and expert opinion available, are a joint effort of the American Cancer Society, the American College of Radiology and the U.S. Multi-society Task Force (comprised of the American College of Gastroenterology, the American Gastroenterological Association [AGA] Institute and the American Society for Gastrointestinal Endoscopy).

“While the AGA Institute considers optical colonoscopy the definitive screening and treatment procedure for colorectal cancer, we support all clinically proven options for colorectal cancer screening. There are many tests available for screening and everyone age 50+ should talk with their physician about what test is available to them,” said John I. Allen, MD, MBA, AGAF, chair of the AGA Institute Clinical Practice and Quality Management Committee.

The panel of experts representing the societies listed above added two new tests as options: stool DNA (sDNA) and CT colonography (CTC). The AGA Institute supports CTC as a promising screening test for colorectal cancer, which we believe will be in widespread clinical use in the near future.

The expert panel also concluded that any proposed colorectal screening test that has not been shown in the medical literature to detect the majority of cancers present at the time of testing should not be offered to patients for colorectal cancer screening, including some types of previously endorsed guiaic-based stool tests.

Based on a review of the historic and recent evidence, the following tests were deemed acceptable options for the early detection of colorectal cancer and adenomatous polyps for asymptomatic adults aged 50 years and older:

Tests That Detect Adenomatous Polyps and Cancer

  • Flexible sigmoidoscopy every 5 years, or
  • Colonoscopy every 10 years, or
  • Double contrast barium enema (DCBE) every 5 years, or
  • CT colonography (CTC) every 5 years

Tests That Primarily Detect Cancer

  • Annual guaiac-based fecal occult blood test (gFOBT) with high test sensitivity for cancer, or
  • Annual fecal immunochemical test (FIT) with high test sensitivity for cancer, or
  • Stool DNA test (sDNA), with high sensitivity for cancer, interval uncertain

The guidelines will appear in the May issue Gastroenterology, May/June issue of CA: A Cancer Journal for Clinicians, and are published early online on CA First Look.