What are the recommendations and screening methods for colon cancer?

There are several methods to screen for colon cancer. The fecal occult blood test is a lab test that can find microscopic amounts of blood in the stool. Because it is inexpensive and available everywhere, this is the most common method used around the world. There are significant limitations to this test, however. Not all polyps or cancer bleed so just because the test is negative, we cannot say with certainty that there are no polyps or cancer present.
Barium enema has fallen out of favor. This screening method uses X-ray to detect large polyps or masses. Small polyps are not detected by this test.
Virtual colonoscopy is an attractive new technology. A CT scan of the colon is used to construct a 3-D image of the colon. This is a good method because it is non-invasive however the technology is not ready for prime time. In addition, patients still have to prepare for the test, cleaning out the colon completely using a prescription laxative solution. This test is very good for finding polyps over six millimeters but accuracy drops to 70 percent for polyps smaller than six millimeters. If this test does find polyps, the patient will still need to have a colonoscopy to remove the polyps.
The colon capsule is another attractive screening option. This is a pill-shaped device enclosing a tiny camera. The patient swallows the camera which then takes pictures as it travels through the digestive tract. As this technology improves, I suspect that in the near future this will become a good option for screening. However, the problem exists that if a polyp is found a colonoscopy will still be required.
The gold standard for colon cancer screening is colonoscopy. In this procedure, a flexible colonoscope is inserted through the anus and used to view the entire lining of the colon. If polyps or other areas of concern are found, they can be removed and/or biopsied during the procedure. It is most important to have a clean prep before your colonoscopy so that the physician can see all areas of the colon.
A flexible sigmoidoscopy is performed in the same manner as a colonoscopy but only examines a portion of the colon.
The screening recommendation is to start at age 50 if there is no family history of colorectal cancer. Screening can consist of a fecal occult blood test every year or flexible sigmoidoscopy every five years or colonoscopy every 10 years. If there is a family history, screening should begin at age 40 or 10 years younger than the relative when he or she had cancer, whichever is earlier. Repeat exam intervals will depend on initial findings.