ASGE encourages patients to speak to their doctor about colorectal cancer screening options

September 18, 2008

Results of the National CT Colonography Trial, published in the September 18 issue of the New England Journal of Medicine, show improvements in the technology's ability to diagnose intermediate- to large-sized polyps in the colon, but this method of testing is not as effective in diagnosing small polyps. CT colonography is one of several colorectal cancer screening options. The American Society for Gastrointestinal Endoscopy (ASGE) encourages patients to speak to their doctor about the screening method that is best for them.

"Colorectal cancer is largely preventable and curable when diagnosed in its early stages. Screening saves lives. Unfortunately, far too few people undergo screening for colorectal cancer. Any advances that result in increased screening of the population are encouraging," said ASGE President John L. Petrini, MD, FASGE. "The results of this trial may prompt those who otherwise would have avoided being tested, to get screened for colorectal cancer. With so many different options to screen for colorectal cancer, it is important to talk to your doctor and discuss which screening method is best for you. Each screening option has appropriate applications and limitations."

CT colonography, also referred to as virtual colonoscopy, relies on a computer program to generate a 3D picture of the large intestine (colon) using x-ray images. This differs from colonoscopy, which provides actual photos of the colon and rectum via a camera attached to a thin, flexible scope that is physically guided through the large intestine.

The results of the National CT Colonography Trial have shown some improvements in the ability of CT colonography to diagnose intermediate- to large-sized polyps. Complete data for 2,531 participants at 15 U.S. centers showed that CT colonography identified large colorectal adenomas (polyps most likely to become cancerous) or cancers 10 mm or larger that were detected by colonoscopy in 9 out of 10 asymptomatic patients. The study also showed that CT colonography had a lower sensitivity for smaller colorectal lesions of 6 to 9 mm in size.

Researchers also reported:

* The sensitivity for the detection of adenomas or cancers greater than or equal to 5 mm, 6mm, 7 mm, 8 mm, 9 mm was 65 percent, 78 percent, 84 percent, 87 percent, 90 percent, respectively.

* If all patients with a lesion measuring 5 mm or more on CT colonography were to be referred for colonoscopy, the colonoscopy-referral rate based on these study results would be 17 percent.

Study participants were asymptomatic, 50 years of age or older and scheduled to undergo routine colonoscopy. Patients were excluded if they had lower abdominal pain, inflammatory bowel disease or familial polyposis syndrome among other exclusionary criteria.

There are, however, concerns about CT colonography's failure to detect small lesions and inability to remove lesions in the colon. Although small polyps often are not cancerous they can be adenomatous polyps and have a risk of developing into cancer. If a polyp is detected through CT colonography, the patient must subsequently undergo a separate colonoscopy to remove the polyp. Most likely, this would happen on another day and the patient would require a second bowel prep before undergoing the colonoscopy.

The primary end point of this study was detection by CT colonography of large adenomas or cancers 10 mm or larger. The radiologists making the interpretations were instructed to record only lesions measuring 5 mm or more in diameter.

It has been suggested that patients with small polyps may be followed by CT colonography at shorter intervals, without referral for colonoscopic removal. This approach of leaving polyps behind has not been tested and it is important to recognize that even small polyps can infrequently harbor early or advanced cancer. Follow up CT examinations will also expose patients to cumulative doses of radiation. Data published in the New England Journal of Medicine (Nov. 29, 2007), pointed to the potential dangers of radiation exposure over a person's lifetime from diagnostic medical testing using CT scans. Recent articles in Time (June 27, 2008) and the New York Times (June 29, 2008) also noted the radiation risks of CT scans. CT colonography could negatively impact the cost-effectiveness of colorectal cancer screening, as each positive CT colonography will require a subsequent colonoscopy.

"ASGE supports colonoscopy for colorectal cancer screening because it offers the advantage of allowing for detection and prevention through the removal of polyps during the same procedure, without unnecessary radiation exposure. Colonoscopy also has a high detection rate for polyps of all sizes and is the only method that allows us to remove polyps before they turn into cancer," said Petrini.

According to a study released in October 2007 from the Centers for Disease Control and Prevention and the American Cancer Society, colorectal cancer deaths dropped nearly 5 percent between 2002 and 2004, more than the other major cancer killers (prostate, breast, lung). Among the key factors playing a role in the decline was prevention through screening and the removal of precancerous polyps. This is excellent news and reinforces the importance of colorectal cancer screening beginning at age 50, or even younger if there is a family history of colorectal cancer or polyps.

If CT colonography is a method patients are considering, they must understand its limitations:

* Requires the same bowel prep as colonoscopy.

* Does not detect small polyps.

* Does not have the ability to remove polyps.

* Requires the insertion of a small tube in the rectum and insufflation of air into the colon.

* Does not require sedation, although air distension of the bowel can be uncomfortable.

* Exposes the patient to radiation.

* Is not currently covered by Medicare as an initial screening test.

* Results from a few select specialized centers have not been replicated elsewhere.

* Currently there is a shortage of people trained to read these scans.

"CT colonography may be best in low risk patients who cannot undergo colonoscopy or who have had an incomplete colonoscopy due to various factors," said Petrini. "Colorectal cancer prevention is a major priority for ASGE, by whichever form it is achieved. Not enough people are getting screened for colorectal cancer and opening a dialogue about screening between the physician and patient is crucial in preventing this disease. Therefore, we will continue to follow developments in all modes of colorectal cancer screening and to critically evaluate which methods are best for patients."

Before undergoing a CT colonography, here are some questions to ask the physician who will perform the procedure:

* What training have you received to perform CT colonography?

* How many CT colonographies have you performed?

* What are complications of the procedure?

* What arrangements will be made if I have a significant finding?

American Society for Gastrointestinal Endoscopy

---

---

	CT Colonography Atlas: For the Practicing Radiologist (Medical Radiology / Diagnostic Imaging) by Emanuele Neri (Editor), Lorenzo Faggioni (Editor), Carlo Bartolozzi (Editor) This easy-to-use atlas comprises a collection of representative common and unusual virtual colonoscopy (CT colonography, CTC) cases that physicians and radiologists may expect to encounter during their clinical practice. The atlas reflects the important recent advances in image acquisition, patient preparation, and image processing and is thus completely up-to-date.  Each case is presented with the native CT images, integrated images obtained by 3D image processing, and colonoscopic correlation. Topics covered include normal appearances, anatomical variants, pitfalls, diverticula, lipomas, inflammatory bowel disease, polyps, flat lesions, cancers, and the postsurgical colon. By presenting the main features of anatomy and pathology, this atlas will serve as an invaluable tool both for...
	CT Colonography: Principles and Practice of Virtual Colonoscopy, 1e by Perry J. Pickhardt MD (Author), David H. Kim MD (Author) In CT Colonography, Perry Pickhardt and David Kim present techniques for quicker evaluation and diagnosis of colon cancer through the pioneering, specialty-changing imaging technique of virtual colonoscopy (VC). This combination of sophisticated X-rays and CT scans of the abdomen offers patients an alternative to colonoscopy that is cost effective and reduces the need for unnecessary polyp removal. Abundantly illustrated in full color, this pioneering book describes CT colonography from pathogenesis, staging and treatment through indications, technique, and interpretation for the most common pathologies. You'll have the full spectrum of VC technique and be able to see procedures performed through video clips on the included DVD.Covers principles, techniques, and interpretations for the...
	CT Colonography, An Issue of Gastrointestinal Endoscopy Clinics, 1e (The Clinics: Internal Medicine) by Jacques VanDam MD PhD (Author), Sughas Banerjee MD (Author) As the debate continues about who should perform CT Colonography, radiologists or endoscopists, this issue marks the first time that the debate is addressed in great detail by BOTH endoscopists AND radiologists. As a result, this issue will be of great interest to both groups. Both offer their point of view on this screening method in great detail. Articles include: Only Radiologists Should Read CT Colonography; Gastroenterologists Should Read CT Colonography; Small and Medium Sized Polyps Noted at CT Colonography Need Not Be Reported; Small and Medium Sized Polyps Noted at CT Colonography Should Be Reported; Role of CTC in a Colorectal Cancer Screening Program; and Establishing a CT Colonography Service, to name a few.
	Colonoscopy best for polypoid lesions: vs. barium enema, colonography.(Clinical Rounds): An article from: Family Practice News by Doug Brunk (Author) This digital document is an article from Family Practice News, published by International Medical News Group on June 15, 2004. The length of the article is 657 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser. Citation Details Title: Colonoscopy best for polypoid lesions: vs. barium enema, colonography.(Clinical Rounds) Author: Doug Brunk Publication: Family Practice News (Magazine/Journal) Date: June 15, 2004 Publisher: International Medical News Group Volume: 34 Issue: 12 Page: 29(1) Distributed by Thomson...
	Accuracy, safety of CT colonography examined.(Gastroenterology): An article from: Internal Medicine News by Jeff Evans (Author) This digital document is an article from Internal Medicine News, published by Thomson Gale on February 1, 2005. The length of the article is 980 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser. Citation Details Title: Accuracy, safety of CT colonography examined.(Gastroenterology) Author: Jeff Evans Publication: Internal Medicine News (Magazine/Journal) Date: February 1, 2005 Publisher: Thomson Gale Volume: 38 Issue: 3 Page: 80(2) Distributed by Thomson...
	Patient's page.(colonography, fecal DNA analysis, Bed sharing): An article from: Southern Medical Journal by Jennifer McKinney (Author), Bridget Garland (Author) This digital document is an article from Southern Medical Journal, published by Thomson Gale on September 1, 2006. The length of the article is 767 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser. Citation Details Title: Patient's page.(colonography, fecal DNA analysis, Bed sharing) Author: Jennifer McKinney Publication: Southern Medical Journal (Magazine/Journal) Date: September 1, 2006 Publisher: Thomson Gale Volume: 99 Issue: 9 Page: 1019(1) Distributed by Thomson...
	CT colonography refines screening for neoplasia.(Digestive Disorders): An article from: Family Practice News by Kate Johnson (Author) This digital document is an article from Family Practice News, published by Thomson Gale on November 1, 2007. The length of the article is 711 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser. Citation Details Title: CT colonography refines screening for neoplasia.(Digestive Disorders) Author: Kate Johnson Publication: Family Practice News (Magazine/Journal) Date: November 1, 2007 Publisher: Thomson Gale Volume: 37 Issue: 21 Page: 37(1) Distributed by Thomson...
	Fecal-tagging prep tested for CT colonography.(Gastroenterology)(computed tomographic): An article from: Internal Medicine News by Kate Johnson (Author) This digital document is an article from Internal Medicine News, published by Thomson Gale on January 1, 2007. The length of the article is 789 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available in your Amazon.com Digital Locker immediately after purchase. You can view it with any web browser. Citation Details Title: Fecal-tagging prep tested for CT colonography.(Gastroenterology)(computed tomographic) Author: Kate Johnson Publication: Internal Medicine News (Magazine/Journal) Date: January 1, 2007 Publisher: Thomson Gale Volume: 40 Issue: 1 Page: 39(1) Distributed by Thomson...
	CT colonography detects bone loss.(News)(computed tomography): An article from: Internal Medicine News by Susan Birk (Author) This digital document is an article from Internal Medicine News, published by International Medical News Group on December 15, 2008. The length of the article is 520 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available immediately after purchase. You can view it with any web browser. Citation Details Title: CT colonography detects bone loss.(News)(computed tomography) Author: Susan Birk Publication: Internal Medicine News (Magazine/Journal) Date: December 15, 2008 Publisher: International Medical News Group Volume: 41 Issue: 24 Page: 1(2) Distributed by Gale, a part of Cengage...
	Medicare advisers back CT colonography, with caveats.(PRACTICE TRENDS)(computed tomography): An article from: Family Practice News by Alicia Ault (Author) This digital document is an article from Family Practice News, published by International Medical News Group on January 15, 2009. The length of the article is 589 words. The page length shown above is based on a typical 300-word page. The article is delivered in HTML format and is available immediately after purchase. You can view it with any web browser. Citation Details Title: Medicare advisers back CT colonography, with caveats.(PRACTICE TRENDS)(computed tomography) Author: Alicia Ault Publication: Family Practice News (Magazine/Journal) Date: January 15, 2009 Publisher: International Medical News Group Volume: 39 Issue: 2 Page: 30(1) Distributed by Gale, a part of Cengage...