Guidelines Issued for Early Detection of Colorectal Cancer

News Author: Laurie Barclay, MDCME
Author: Penny Murata, MD

March 10, 2008 — The American Cancer Society has issued guidelines for the screening and surveillance for the early detection of colorectal cancer (CRC) and adenomatous polyps in asymptomatic, average-risk adults. The new consensus guidelines, which were jointly developed with the US Multi-Society Task Force on Colorectal Cancer and the American College of Radiology, beginning in 2006 to 2007, are published in the March 5 First Look issue of CA: A Cancer Journal for Clinicians and will appear in the May-June 2008 print issue.

"In the United States, colorectal cancer (CRC) is the third most common cancer diagnosed among men and women and the second leading cause of death from cancer," write Bernard Levin, MD, from The University of Texas M.D. Anderson Cancer Center in Houston, Texas, and colleagues from the American Cancer Society Colorectal Cancer Advisory Group, the US Multi-Society Task Force, and the American College of Radiology Colon Cancer Committee. "CRC largely can be prevented by the detection and removal of adenomatous polyps, and survival is significantly better when CRC is diagnosed while still localized."

This update of each contributing organization's guidelines groups screening tests into those that primarily detect cancer early and also can detect adenomatous polyps, thus offering a greater potential for prevention through polypectomy.

Clinicians should make patients aware of the full range of screening options whenever feasible. At a minimum, however, clinicians should be prepared to offer patients a choice between a screening test that is effective at both early cancer detection and cancer prevention through the detection and removal of polyps and a screening test for which benefits are primarily limited to early detection of cancer. The 3 sponsoring organizations strongly concur that the main goal of screening should be the prevention of CRC.

"In the last decade, there has been an increase in the number of technologies available for CRC screening, and in the case of stool tests, there has been growth in the number of commercial versions of guaiac-based and immunochemical-based stool tests (gFOBT [guaiac-based fecal occult blood test] and FIT [fecal immunochemical test])," the authors of the guidelines write. "It is our hope that these new recommendations will facilitate increased rates of CRC screening and that referring clinicians find these new guidelines ease some of the challenges they have experienced in promoting CRC screening to their patients."

In the first phase of the guidelines update process, stool tests were reviewed, including the gFOBT, the FIT, and the stool DNA test (sDNA). In the second phase, the panel developed recommendations for the structural examinations, including flexible sigmoidoscopy (FSIG), colonoscopy, double-contrast barium enema (DCBE), and computed tomographic (or virtual) colonography (CTC).

The panel discussed these issues, heard presentations from outside experts, relied on previous evidence-based reviews, and searched MEDLINE (National Library of Medicine) and bibliographies of identified articles for literature related to CRC screening and specific to individual tests published between January 2002 and March 2007. When evidence was insufficient to provide a clear, evidence-based conclusion, final recommendations were based on expert opinion.

Testing options for the detection of adenomatous polyps and cancer for asymptomatic adults 50 years and older include FSIG every 5 years, colonoscopy every 10 years, DCBE every 5 years, or CTC every 5 years.

Testing options that primarily detect cancer in asymptomatic adults 50 years and older include annual gFOBT with high-test sensitivity for cancer; annual FIT with high-test sensitivity for cancer; or sDNA with high-test sensitivity for cancer, although the optimal interval for sDNA is uncertain.

Each screening test has unique advantages, has been shown to be cost-effective, and has associated risks and limitations. Ultimately, patient preferences and availability of testing resources guide the selection of screening tests.

The disadvantages of the structural tests are that they require bowel preparation, but their primary advantage is that they can detect polyps as well as cancer. Conscious sedation is used for colonoscopy. FSIG is uncomfortable, and screening benefit is limited to the portion of the colon that is directly examined.

Risks for colonoscopy, DCBE, and CTC may rarely include perforation; colonoscopy may also be associated with bleeding. Positive findings on FSIG, DCBE, and CTC usually result in referral for colonoscopy.

The advantages of the stool tests are that they are noninvasive, they do not require a bowel preparation, they can be done in the privacy of the patient's home, and they are more readily available to patients without adequate insurance coverage or local resources.
However, these noninvasive tests are less likely to prevent cancer vs the invasive tests; they must be repeated at regular intervals to be effective; and, if the test is abnormal, an invasive test, namely colonoscopy, will be required. For patients who are unwilling to have repeated testing or to undergo colonoscopy if the test results are abnormal, stool testing is ineffective and should not be recommended.

This update of the CRC screening guidelines focused on screening in average-risk adults and did not consider evidence concerning CRC screening or surveillance for individuals at increased and high risk. Patients with a personal history of adenomatous polyps or curative-intent resection of CRC, a family history of either CRC or colorectal adenomas diagnosed in a first-degree relative before age 60 years, or a history of inflammatory bowel disease of significant duration or 1 of 2 hereditary syndromes should continue to follow recommendations issued previously by the American Cancer Society or the US Multi-Society Task Force for individuals at increased risk.
"There is compelling evidence to support screening average-risk individuals over age 50 years to detect and prevent CRC," the panel concludes. "Screening of average-risk individuals can reduce CRC mortality by detecting cancer at an early, curable stage and by detecting and removing clinically significant adenomas. . . . No CRC screening test is perfect, either for cancer detection or adenoma detection."

Some of the authors of the guidelines have disclosed various financial relationships with Exact Sciences, Vital Images, Medicsight, Covidien, Viatronix, Fleet, Olympus, Given Imaging, Avantis, NeoGuide, G.I. View, American BioOptics. Genzyme, Epigenomics, GeneNews, and licensure of a CT colonography software patent to GE Medical Systems.

CA Cancer J Clin. Published online March 5, 2008.

Clinical Context
CRC is the third most common cancer in men and women in the United States and is the second leading cause of deaths from cancer, as reported by Jemal and colleagues in the March-April 2008 issue of CA: A Cancer Journal for Clinicians. Tools for CRC screening include stool tests for occult blood or exfoliated DNA to detect cancer and structural examinations to detect adenocarcinoma and identify adenomatous polyps. Stool tests include the gFOBT, the FIT, and the sDNA. Structural examinations include FSIG, colonoscopy, DCBE, and CTC.

The American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology have collaborated on guidelines for the detection of adenomatous polyps and CRC in asymptomatic, average-risk adults 50 years or older.

Pearls for Practice
Stool test screening options to detect CRC in asymptomatic, average-risk adults 50 years and older include the annual high-sensitivity gFOBT, the annual FIT, or the sDNA test at uncertain intervals.

Structural examination screening options to detect CRC and adenomatous polyps in asymptomatic, average-risk adults 50 years and older include FSIG every 5 years, colonoscopy every 10 years, DBCE every 5 years, or CTC every 5 years.

(Source: Medscape)