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The Importance of Colorectal Cancer Screening

Cancer screening is usually not a convenient or pleasurable part of health care maintenance. Men who have had digital rectal exams for prostate cancer as well as women who undergo yearly PAP smears for cervical cancer can certainly attest to that. Yet nothing brings a frown to the face faster than a recommendation for colorectal cancer screening. However, the potential life-saving benefit has been proven to be worth the inconvenience.

Colorectal cancer is the second most common cause of cancer-related deaths in the United States and the third most common cancer overall. While it sometimes may be too late once this cancer is discovered, precancerous lesions in the colon (polyps) can be easily removed in their early stages. These polyps occur in up to a third of people over the age of 50 and their number increase with age. The risk of getting colorectal cancer is markedly decreased by their removal.

We are all at risk of developing colorectal cancer over our lifetime, but certain conditions make it more common. As mentioned, the incidence of polyps increases with age, and those who are genetically predisposed to develop multiple polyps at earlier ages have the greatest risk. Those who have a family history of colon cancer, those with other gastrointestinal conditions such as ulcerative colitis or Crohn's disease, and those who are long-term smokers have the highest risks, while those with a previous history of colon cancer are prone to developing it a second time.

What are the most common and effective ways to screen for colorectal cancer? Early detection of blood in the stool can be detected using fecal occult blood testing (FOBT). Usually doctors send home testing cards with the patient. While easy to do, this type of test often misses polyps that are not yet bleeding and has a significant amount of false positive testing. In other words, it may not pick up the cancer it is trying to find, and if positive, may result in the more aggressive testing that the home testing cards seek to avoid.

A sigmoidoscopy done every five years is accepted as an effective screening test by most medical organizations. The testing shows a very significant mortality benefit for those who undergo it. A flexible sigmoidoscope is passed through the rectal area and visualizes the colorectal area directly. However, it doesn't get to areas higher than the lower colon and the procedure requires a thorough cleansing of the colon, which many say is as unpleasant as the testing.

A colonoscopy every 10 years has the highest single-test accuracy of all the screening procedures.  Here, the rectal area and the entire colon are visualized directly through use of a colonoscope. As sedation is given before the procedure, it is most often not of any major discomfort to the patient, but it does require the same thorough cleansing of the colon before the procedure.

Virtual colonoscopy is the newest and perhaps most controversial of the colon screening methods. In effect, it is a CT scan of the colon. The pictures obtained can show polyps or growths without introducing a scope into the body. It is less invasive as a result and doesn't require sedation. The sensitivity and specificity of the test are good, but as many as 15% have questionable findings that require definitive and diagnostic colonoscopy, in addition to the imaging.  Of course, this procedure also requires the same internal cleansing each time.

As colon cancer is such a potential killer, consult with your doctor on your next wellness exam to see what he recommends and which screening procedure would be most efficacious and cost effective for you. It is certainly worth the inconvenience.

Authored by Dr. Bob Goldstone, M.D.

The information contained on this page is not intended to provide medical advice, which should be obtained directly from your physician.