Updated colorectal screening guidelines add new tests

Joint updated  colorectal cancer screening guidelines to find colon and rectal cancer early and to detect precancerous polyps (adenomas) were published yesterday by the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.  Removing adenomatous polyps before they become malignant can prevent colorectal cancer.

For the first time, screening tests are grouped into two categories:

  • Tests that detect adenomatous polyps and cancer.
  • Tests that primarily detect cancer.

Two additional tests were added to recommended screening tests for average risk men and women:

  • Stool DNA (sDNA) testing was added to the tests that primarily detect cancer.
  • CTC or virtual colonoscopy, is now included in tests that detect polyps and cancer.

The expert panel that developed the new guidelines emphasized their opinion that colorectal cancer prevention should be the primary goal of screening.

Testing 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
  • Colonoscopy every 10 years
  • Double-contrast barium enema every 5 years
  • Computed tomographic colonography every 5 years

Tests that Primarily Detect Cancer

  • Annual guaiac-based fecal occult blood test with high test sensitivity for cancer
  • Annual fecal immunohistochemical test with high test sensitivity for cancer
  • Stool DNA test with high sensitivity for cancer, interval uncertain.

The guidelines are a consensus of experts from

  • American Cancer Society
  • US Multi-Society Task Force on Colorectal Cancer
    • American College of Gastroenterology
    • American Gastroenterological Association
    • American Society for Gastrointestinal Endoscopy.
  • American College of Radiology

The panel reviewed previously known and new evidence for effectiveness and safety of methods to test for colorectal cancer and the adenomatous polyps that lead to it.  They weighed risks and benefits for each method before coming to consensus on the updated recommendations.

In dividing test methods between those that primarily detect cancer and those able to find precancerous polyps, the expert panel emphasized the importance of cancer prevention:

It is the strong opinion of this expert panel that colon cancer prevention should be the primary goal of CRC screening.

Tests that are designed to detect 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 partial or full structural exams mentioned above. These tests require bowel preparation and an office or hospital visit and have various levels of risk to patients. These tests also have limitations, greater patient requirements for successful completion, and potential harms.

Significant positive findings on FSIG, DCBE, and CTC require follow-up colonoscopy.

However, they recognized that some people may not want to undergo invasive tests requiring bowel preparation, may prefer a test that they can do privately at home, or may not have access to preventive tests because of lack of insurance coverage or local resources.  In those situations, patients and doctors should understand that fecal tests that primarily detect cancer:

  • Are less likely to prevent cancer compared with the invasive tests.
  • Must be repeated at regular intervals to be effective.
  • An invasive test (colonoscopy) will be necessary if a fecal test is abnormal.

C3 Colorectal Cancer Coalition Founding Member and Research Advocate Pamela McAllister,PhD participated in the development of the updated guidelines as a member of the American Cancer Society Colorectal Cancer Advisory Group.

Bernard Levin, MD, Professor Emeritus at the University of Texas MD Anderson Cancer Center in Houston was the lead author of the paper that appears in CA: A Cancer Journal for Clinicians, Gastroenterology, and Radiology.

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