March 6, 2008 -- Colon cancer experts today issued new guidelines about colon cancer screening tests.
The new guidelines, which emphasize colon cancer prevention, come from the American Cancer Society, the U.S. Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology.
Here's the simplest guideline: If you're age 50 or older, you need to get routine screening for colon cancer. If you're at high risk, you may need to start screening before 50. That recommendation isn't new, but it often goes unheeded.
Tests done inside the body can spot cancer and polyps (abnormal growths that may develop into cancer). Stool tests primarily focus on detecting cancer, not polyps, according to the American Cancer Society.
Here are the American Cancer Society's recommendations for both types of tests.
Tests for Cancer and Polyps
If you're looking for a test that can spot cancer and polyps, the American Cancer Society recommends choosing between these options:
- Flexible sigmoidoscopy every five years, or
- Colonoscopy every 10 years, or
- Double-contrast barium enema every five years, or
- "Virtual colonoscopy" (computed tomographic colonography) every five years
This is the first time that virtual colonoscopy has made the American Cancer Society's list of acceptable screening tests.
If you're looking for a stool test, here are the choices recommended by the American Cancer Society.
- Annual guaiac-based fecal occult blood test (gFOBT) with high test sensitivity for cancer, or
- Annual fecal immunochemical test (FIT) with high sensitivity for cancer, or
- Stool DNA (sDNA) test with high sensitivity for cancer (optimal interval between tests unknown)
The American Cancer Society notes that stool tests are less likely to prevent cancer than tests that look for cancer inside the body. Also, stool tests must be regularly repeated. And if a stool test finds blood in stools, patients should get a colonoscopy.
About the Tests
Here is a quick look at the recommended tests:
- Flexible sigmoidoscopy: Doctors use a thin, flexible tube with a tiny camera to examine the rectum and the lower part of the colon.
- Colonoscopy: Similar to flexible sigmoidoscopy, but includes the entire colon.
- Double-contrast barium enema: An X-ray test used to picture the inside of the colon.
- Virtual colonoscopy: Uses CT scans to picture the inside of the colon.
- gFOBT: Checks for blood in stool samples. If blood is found, the patient should get a colonoscopy.
- FIT: Checks for blood in stool samples, using a different technique than the gFOBT test. If blood is found, the patient should get a colonoscopy.
- sDNA: Checks stools for colorectal cancer DNA.
The new guidelines are posted in today's advance online edition of CA: A Cancer Journal for Clinicians.